EAT, FAST AND LOSE WEIGHT
THE TRUTH ABOUT FAT AND WEIGHT LOSS
These days, in countries where there’s an abundance of food, we’ve become used to constant grazing – rarely sitting down for meals and simply picking at high-calorie, high-fat and high-sugar foods all day long. We’ve forgotten what it feels like to be really physically hungry.
The unfortunate truth is that many of us are designed to get fat. It all comes down to evolution. Back in the dim and distant past, when food shortages were common, people who had substantial fat “in storage” were more likely to survive.
Research carried out in the last century proved that extended periods of starvation are much less dangerous for people who have high levels of body fat – in fact, the heavier you are, the more likely it is that fasting will lead to substantial fat loss with muscle being spared. In contrast, the slimmer you are (and your ancestors were), the more likely it is that you’ll break down muscle through extreme dieting.
People often blame their genes for a “slow metabolism” or “big bones”, but it turns out things are more complicated than that. The genetic factors that helped your ancestors lay down fat stores seem to relate to a complex range of factors rather than simply affecting your metabolic rate. For example, there are subtle differences in appetite, or in the tendency to fidget.
Abdominal fat (sometimes called visceral fat) is found deep in your body surrounding your internal organs, whereas subcutaneous fat lies just below the surface of your skin – the stuff you can pinch with your fingers. You may think that being a little heavy around your middle isn’t such a bad thing, but unfortunately recent research shows that excess fat in this area – rather than on your thighs or bottom – increases your risk of diabetes, heart disease, stroke, high blood pressure and even certain cancers. Scientists have found that abdominal fat is more biologically active than other fat cells in the body, meaning it produces more hormones and other biochemicals that can have a profound effect on your health. For example, abdominal fat produces immune system chemicals called cytokines, which have been shown to increase your risk of cardiovascular disease by promoting insulin resistance and low-level inflammation.
WHY SOME PEOPLE ARE NATURALLY SLIM
Emerging research suggests that naturally slim people have genetic advantages that make it easier for them to avoid weight gain. They’re not blessed with faster metabolisms, but tend to be able to regulate their appetite and burn off excess calories without even noticing it.
TO THEM, FOOD IS JUST FOOD
Naturally slim people enjoy food, but they don’t have a strong emotional connection to it. Foods aren’t “good” or “bad”, they’re just food. Therefore, slim types don’t feel guilty when they tuck into a slice of cake or have a few chips with their dinner.
THEY CAN STOP AFTER JUST ONE BITE
When our naturally slim friends eat indulgent foods, they can stop after just a little, rather than polishing off the plate. Many of us are familiar with that feeling of having broken the diet rules:
“That’s today ruined… I may as well finish the whole cake and start again tomorrow.”
Slim people don’t get that “all-or-nothing” feeling that’s typical in seasoned dieters.
THEY RECOGNIZE THE DIFFERENCE BETWEEN HUNGER AND APPETITE
The mechanisms controlling our appetites are complex. Research suggests that naturally slim people may be more resistant to appetite signals that aren’t linked to physiological hunger. What this means is, they eat when their body needs nourishment, not when their brain is trying to trick them into believing they’re hungry. In contrast, those of us with a genetic tendency to gain weight can feel physically hungry when tempted by food, even if our bodies don’t need the calories.
THEY BURN IT OFF
There’s a theory that our body weight has a “set point” (a natural weight at which it tries to maintain itself). When a naturally slim person overeats, they tend to compensate by moving around more, without even thinking about it. So, as well as a few more gym sessions, they may fidget, get stuck into cleaning the house, or walk rather than taking the car. But for the majority of us, overeating is followed by a few hours relaxing on the sofa!
In studies where people have been limited to four hours’ sleep a night for several days, changes in appetite hormones have been observed, and the appetite for sweets, salty snacks, fatty and starchy foods seems to increase. Through sleeping longer, our naturally slim friends may find that they’re less tempted to snack. There are more than 65 published research papers that have linked sleeping for fewer than six hours a night with increased weight. When researchers at the University of Warwick analyzed all the evidence on the relationship between sleep and obesity, they found that adults who slept for fewer than five hours a night were one-and-a-half times more likely to be obese!
OTHER FACTORS INFLUENCING WEIGHT
Ultimately, weight gain comes down to the fact that we’re eating more calories than we’re burning off, and over time this has led to many of us gradually getting fatter. But tackling the issue is about more than simply cutting calories. The quality of what we eat is important too. The types of food that are so readily available to us – those muffins and sugary drinks – tend to be packed with sugar or refined carbohydrates (carbs) and it’s very easy to eat them and not notice when we’re full. Instead, try replacing those “empty” calories with nutrient-rich, lean proteins, leafy green vegetables and even healthy fats from nuts and oily fish. I promise you, these will make you feel full and you’ll be much less tempted to overeat.
It’s also important to detect underlying problems or habits that can be causing or contributing to a weight problem. For example, stress, emotional eating or chemical calories may have been the tipping point for your body. Unhealthy eating can mean that you’re not getting enough of the vitamins, minerals and essential fats that your body needs to function well. What’s more, many “fad” diets aren’t nutritionally balanced, so they starve the body of the vital nutrients your body needs.
On a basic level, these problems can make it very hard for you to stick to a diet. Likewise, “crash” diets tend to drastically restrict your body’s intake of calories. If your body isn’t getting the nutrients it needs, the result can be irritability, depression and even lowered brain function, all of which inevitably affect your motivation to continue with the diet. And when you come off the diet, you quickly return to your previous weight and may end up gaining even more weight. This is because, when you lose weight, your metabolic rate naturally dips – more about this shortly.
STRESS AND WEIGHT GAIN
The link between stress and weight gain begins with tiny glands called adrenals. Their basic task is to rush all your body’s resources into “fight or flight” mode by increasing production of adrenaline and other hormones – you may recognize this feeling with an increased heart rate, and your blood pressure may be raised.
Unlike our ancestors, who weren’t distracted by mobile phones, deadlines, emails and the multi-tasking challenges of modern life, today we live under constant stress. Instead of occasional, acute demands followed by rest, we’re constantly over-worked, under-nourished, exposed to environmental toxins, and plagued by worries… with no let-up.
Every challenge to the mind and body creates a demand on the adrenal glands. The result is a state of constant high alert and high levels of the hormone cortisol in the body, leading to a huge number of health problems, such as a tendency to hold on to stubborn belly fat. The other main side-effects of stress and adrenal overload are digestive problems, rapid ageing, lowered immunity and skin problems.
Sometimes it’s less about the stress in our lives and more about the stress we place on ourselves with what we eat and drink. Take caffeine, for example. We’re all familiar with the “buzz” that caffeine can give. Many products are marketed solely on the basis of this false energy kick, but that lively feeling is actually the sensation of adrenaline being pumped around the body as a result of the caffeine hit. The adrenal glands tire of constant stimulation and when the inevitable adrenal fatigue kicks in, it leads to a slowdown in the conversion of stored fats (and proteins and carbohydrates) into energy. We experience this failure in the energy chain as a craving for further stimulants in the form of more caffeine from another cup of tea, coffee, cola drink or caffeinated beverage. The last piece of the picture with caffeine is what usually comes with it. Remember that an average coffee these days contains a sizeable portion of milk, sugar or syrup and then there’s the ubiquitous temptation of a muffin or pastry accompaniment!
INSULIN RESISTANCE AND THE EFFECTS OF ALCOHOL
When the body is overloaded with carbs (which are extremely commonplace in the average Western diet), it has to respond by making more insulin. Carbs are broken down into molecules of the sugar glucose, and insulin is the hormonal “key” that unlocks the cells to allow the glucose in. Over a period of time, excess insulin affects the cells by making them less sensitive to taking sugars into the cell and creating energy. This in turn prevents the cells from burning fat. The good news is that fasting may improve how your body handles sugar and help your body burn fat instead of storing it.
As far as your body’s concerned, alcohol is chemically similar to sugar, so drinking any form of alcohol will set off the same insulin resistance seesaw that can promote weight gain. And that’s before you even begin to consider the calorie content of the drink itself, which is likely to be very high and devoid of any nutritional benefit – so-called “empty calories”. What’s more, alcohol acts as a potent appetite booster, so more alcohol equals more food consumed!
There’s yet another reason behind alcohol’s “beer belly” effect. Alcohol reduces the amount of fat your body burns for energy, while preventing the absorption of many of the essential nutrients needed for successful weight loss, particularly the B vitamins and vitamin C. In one study published in the American Journal of Clinical Nutrition, eight men were given two glasses of vodka with diet lemonade, each containing just under 90 calories. For several hours after drinking the vodka, the amount of fat the men burned dropped by a massive 73 percent. Because your body uses more than one source of fuel, if alcohol is consumed then this alcohol “energy” will be used instead of fat – not good news for the waistline!
EMOTIONAL EATING
As we all know, a lot of eating is emotionally driven. Many people with weight problems fear feeling hungry. Furthermore, reaching for the sugar-fix from food or from alcohol is what helps free us, temporarily, from whatever uncomfortable emotion we might be feeling. Of course, sometimes an eating problem masks an underlying psychological problem or challenge. In such cases, expert advice, counselling or psychotherapy or psychology can really help.
Even when eating is free from emotional factors, the fact is, the longer you spend on a diet (whether for health or for weight loss), the less strict you become and the more likely it is that calories will sneak in without you noticing – a bite of this here, a nibble of that there. Fasting shakes up this model of eating altogether. Having a large section of the day when food simply isn’t allowed to pass your lips prevents random snacking, and might also alert you to how often you do this normally. If you’d describe yourself as someone with limited self-control, fasting is an easier option than almost any other diet out there as you don’t have to count every calorie or become a slave to food group fads – the only thing you really need to do is watch the clock.
“CHEMICAL CALORIES”
It’s thought that chemicals in the environment have a blocking effect on the hormones that control weight loss. When the brain is affected by these toxins, hormone signalling can be impaired. Reducing chemicals in our homes, foods and drinks is important when looking at the overall picture of weight loss and health. As you’ll discover in the “Nutritional Rules for Fasting” chapter, one of my nutrition rules as part of any fasting programme is to eat real food rather than fake food. If you can’t pronounce what it says on the label, you probably shouldn’t be eating it!
THYROID PROBLEMS
An underactive thyroid can cause weight gain, too. Symptoms include fatigue, cold, hormonal problems, depression and low libido as well as unexplained weight gain. The challenge is sometimes that the problem is sub-clinical, in other words, your test from the doctor may come back negative but you still have the symptoms. This can be frustrating for the sufferer as it sometimes means a re-visit in six months to a year to see if the symptoms register as qualifying for medical intervention.
A nutritious diet designed with thyroid health in mind can help. For the thyroid to work optimally, it needs nutrients such as iodine, manganese, vitamin C, methionine, magnesium, selenium, zinc, and the amino acids cysteine and L-tyrosine. These are all found in healthy foods such as fruit, vegetables, nuts, seeds and meat.
WHAT YOU SHOULD WEIGH
Before you embark on a fasting programme for weight loss, let me help you establish what you should weigh. For many people, women in particular, the figure we think of as “ideal” is far removed from what is realistic, or even healthy. I could go on and blame the media or the fashion industry. We all know that argument and, yes, it’s partly true.
Ironically, where I learned about fasting in India, the thought of using fasting to get slim would be abhorrent, as being skinny is associated with poverty and lower social castes. Fasting should never be used to strive for a body that’s slimmer than is healthy – the size zero craze being a case in point. The less body fat you have to lose, the more you need to ensure that fasting is not over-done since weight loss is a guaranteed side-effect.
BODY MASS INDEX (BMI)
Healthy weight ranges are especially useful if you’re already light for your frame – you’ve probably heard of BMI, which gives an indication of how healthy your current weight is in proportion to your height. The formula for calculating BMI is:
BMI = weight (kg) ÷ height (m)2
(in other words, your weight in kilograms divided by your height in metres squared).
If maths isn’t your strong point, you can find out your BMI using an online calculator.
A healthy BMI is between 18.5 and 24.9. Although many celebrities have a BMI below 18.5, this simply isn’t healthy. Some studies suggest that the ideal BMI is 23 for men and 21 for women – particularly if it’s a long and healthy life you’re after.
However, if your BMI is, say, 25 you won’t become magically healthier by losing 450g (1lb) and dieting down to a BMI of 24.9. In fact, it’s perfectly possible for someone with a BMI of 27 to be much healthier than someone with a BMI of 23. That’s because BMI doesn’t take your body fat, waist circumference, eating habits or lifestyle into account. An example of this could be a professional rugby player who’s heavier than average simply because he or she is very muscular. There’s nothing unhealthy about having lots of muscle, but the BMI scale might say he or she is overweight or even obese. In contrast, a chain-smoker who lives on diet drinks and never exercises can have a so-called “healthy” BMI. Who do you think is healthier?
A BMI of 30 or above is considered “obese”. A 2008 study by researchers at the Mayo Clinic in the USA, involving over 13,000 people, found that 20.8 percent of men and 30.7 percent of women were obese according to the BMI scale. But when they used the World Health Organization gold standard definition of obesity – measuring body fat percentage – 50 percent of the men and 62.1 percent of the women were classified as obese. (In other words, you can have a healthy BMI and an unhealthy level of body fat.) What this means is that the athlete who’s unfairly classed as “obese” is the exception rather than the rule. Unless you’re an avid weight-lifter or sportsperson, or you have an extremely physical job, the BMI scale isn’t likely to tell you that you need to lose weight if you don’t. If your BMI is well over 25, don’t worry. Medical experts agree that losing 5–10 percent of your starting weight is a sensible and realistic initial goal that will have lasting health benefits.
Therefore, when it comes to the BMI scale, it is worth calculating your BMI before deciding on a weight loss goal, especially if you only have a little weight to lose, but it definitely shouldn’t be the only thing you think about.
BODY FAT PERCENTAGE
What’s great about monitoring your body fat percentage is that it gives you a better understanding of what’s going on inside your body as you lose weight. Sustainable weight loss is best achieved through a combination of good nutrition and an active lifestyle. The thing is, when you start exercising more, you often gain muscle mass.
It can be demotivating to step onto the scales and see that your overall weight hasn’t changed in spite of all your hard work. But because muscle is more dense than fat, you can look slimmer and achieve health benefits without actually losing weight. To track changes in your body fat, you need to invest in body composition scales which enable you to track your progress by measuring changes in your muscle mass, body fat and hydration. Gyms often have high-quality versions of these scales if you don’t want to buy your own.
Body composition scales are also helpful because if you notice that your muscle mass is decreasing as rapidly as your body fat, this suggests that you’ve cut your energy intake too dramatically. For most people, it’s realistic to lose 450–900g (1–2lb) of body fat per week. If you’re losing much more than this, the chances are you’re eating into your muscle mass. Body composition scales can alert you to this before you’ve risked damaging your health.
In women, it’s normal for hydration levels to fluctuate along with the menstrual cycle. Again, measuring weight alone doesn’t enable you to track these changes. By using the body composition scales at a similar time of day, and recording changes throughout the month, you can get a clearer understanding of the times you’re gaining body fat, and when it’s simply a matter of fluid retention.
Sophisticated body composition monitors also enable you to track abdominal fat. Remember, not all fat is created equal, and abdominal fat is concentrated around your vital organs, posing the biggest health risk. You can be a “healthy” weight, and have high levels of abdominal fat – being aware of this can give you the motivation you need to address your eating habits and activity level.
The scales use a weak electric current to differentiate between fat, muscle, fluid and bone – we won’t go into too much detail here as different brands have different features. As a guide, if you’re an ordinary adult, and not an athlete or aspiring fitness model, you should be aiming for the following body fat percentages:
| AGE | MALE | FEMALE |
| 20–39 | 8–20% | 21–33% |
| 40–59 | 11–22% | 23–34% |
| 60+ | 13–25% | 24–36% |
WAIST CIRCUMFERENCE AND WAIST-TO-HIP RATIO
One of the most useful basic measurements is the waist-to-hip ratio (WHR). It all goes back to apples and pears. Not about eating them, although that would be a good start, but which one your body shape is most like. Your WHR will put you either in the “apple-shaped” category (with more weight around the waist) or “pear-shaped” (with more weight around the hips).
I like the WHR because it’s fairer than BMI, which doesn’t take varying body structures into account. Put it this way… a curvaceous “Marilyn Monroe type” with a nipped-in waist can have exactly the same WHR as a 50kg (8st), size-8 slip of a girl. If you’re someone who’s using fasting to get your body into supermodel shape, you’ll be interested in the calculation below.
Actress and model Liz Hurley has a WHR of 0.7 – even her face is said to be perfectly proportioned. Scientists have gleefully spent hours locked away in dark cupboards sizing her up (okay, I made the last bit up, but the scientists are real). They have declared that she’s scientifically and statistically proven to be nature’s perfect woman. However, like most models, Liz has just lucked out genetically. A WHR of below 0.8 is ideal for women. For men, those with a WHR score of 0.9 or below tend to be healthier. The important thing is that if your WHR is higher than this, you should be working on your shape as much as on your weight.
CALCULATING YOUR WHR
Calculating your WHR is fairly simple. Get out a tape measure and measure the circumference of your hips at the widest part. You can do it in centimetres or inches. Next, measure the smaller circumference of your natural waist (usually just above the belly button). To determine the ratio, divide your waist measurement by your hip measurement.
Ideally, aim to keep your waist circumference below 94cm (37in) if you’re a man and below 80cm (31in) if you’re a woman. If your waist is larger than 102cm (40in) if you’re a man or 88cm (35in) if you’re a woman, this is putting you at increased risk of health conditions such as diabetes and heart disease. As you’ll discover in the “Eat, Fast and Perform Better” chapter, fasting is a great way to reduce body fat and maintain lean muscle, which will help get your waist into a healthier shape.
WHY TRADITIONAL DIETING MAKES YOU HUNGRY
Going on a traditional diet without adequate energy intake for long periods of time can make your metabolic rate plummet and your appetite soar. Say you reduce your calories to below 1,000 a day for a number of weeks to fit into a party dress, the chances are you’ll feel hungry and fed up much of the time, and as soon as the party starts, you’ll dive head first into all the foods you’ve been avoiding, re-gaining that lost weight in no time! This, in a nutshell, sums up the seesaw of the diet industry.
The real trick is to keep your body feeling fuller for longer. I’m not talking about choosing one ready-meal over another, it’s about understanding how to manage hunger so you naturally eat less most of the time. Please note, I don’t say all of the time. Special events and over-indulging every now and then is good for the soul.
In tandem with a good diet overall, fasting can be used to retrain your hunger without the need for appetite suppressants or dodgy supplements. When you begin to fast you will feel hungry at your usual meal times. However, if you choose not to eat at that time, the peaks and troughs of hunger start to level out. All this happens without a decrease in metabolic rate. It doesn’t take a genius to recognize that if you feel hungry less often, you’ll eat less and therefore lose weight. There’s a biological explanation for this. Feelings of hunger and satiety (feeling full) are controlled by two main hormones produced within the body, ghrelin (even the word sounds hungry) and leptin. This dynamic duo of hormones has a powerful effect on how much food you eat and how much of what you’ve consumed you “burn off”.
This hormone seems pretty straightforward. When your stomach’s empty, it sends out some ghrelin to tell an area of your brain, the hypothalamus, that you ought to be eating. You then feel ravenous. But research published in the American Journal of Physiology suggests that ghrelin levels also rise in anticipation of eating – you get hungry partly because you’re expecting a meal, not just because you have an empty stomach.
On a traditional diet, you get a peak of ghrelin before every meal – but because you don’t eat as much as you’d really like to, you never feel fully satisfied. When you’re fasting, your ghrelin levels still rise, but anecdotal evidence suggests that over time your body finds this sensation easier to get used to, probably because of the changes in your meal patterns. There’s also a theory that a nutritionally poor diet (think additive-packed “diet” meals) sends ghrelin rocketing faster than a nutrient-dense plan like the ones I recommend (see pages 178–80).
LEPTIN
This hormone is a little more complicated. You’ll sometimes hear leptin referred to as a “master regulator” of fat metabolism. There are even whole diet books devoted to it.
Leptin is made by the fat cells – put simply, the more fat you have, the more leptin is produced. Like ghrelin, it sends a signal to the hypothalamus, but with the opposite effect. Leptin is supposed to maintain your body fat at a healthy level by telling you to stop eating when you start to gain too much fat. We all know it doesn’t really work like that in practice – if it did, no one would be overweight. So, what happens?
Well, leptin also increases when you overeat – especially stodgy, carbohydrate-rich meals. This is because its release is triggered by insulin, which responds to an increase in blood glucose after a meal. So, if you’re constantly eating without a proper break, your leptin levels will always be high. At first this is good – it should signal to your brain that it’s time to put down that muffin – but it can lead to a very dangerous vicious circle. The theory is that, over time, too much leptin leads to the brain becoming resistant to its effects. As your brain stops recognizing what leptin is trying to tell it, you end up feeling hungry all the time, and are never satisfied by even the biggest meal.
When you follow a traditional weight-loss diet the reduction in your body fat means that your leptin levels fall. Combine that with the rise in ghrelin and you’ll understand why you feel driven to eat and eat. The “yo-yo” diet cycle begins. In fact, Australian researchers have found that leptin and ghrelin levels can be messed up for more than a year after you reach your target weight. Your body’s doing everything it can to gain that fat back.
Compare this with intermittent fasting. Some studies suggest that leptin levels fall after 12–36 hours of fasting, but others show no evidence of a change within up to 24 hours. Even if fasting does send your leptin levels plummeting, they quickly go back to normal when you start to eat – especially if your meals are rich in carbohydrates. So, rather than having lower leptin all the time (like you do on a normal diet), those days or meals when you eat “normally” during fast and feed cycles mean that your body gets a boost of leptin and feels more satisfied.
WHY MOST DIETS FAIL
This probably isn’t the first book about weight loss you’ve ever read. I often say I’ve been down the diet road myself so many times that I could be a tour guide. If you’re asking yourself why fasting is going to be any different, here are the facts you need to know:
•“Yo-yo” dieting is the bane of many people’s lives, but even if you’ve lost and gained weight countless times, recent research has shown that it’s possible to lose weight safely without messing up your metabolism.
•Burning off more calories than you eat is the only way to lose weight – and the simple truth is that you will lose weight if you manage to keep the number of calories you eat below the amount you burn off… boring but true.
There are hundreds of different ways to create a calorie deficit – as evidenced by the huge diet book, diet shake, diet bar and “miracle” weight-loss supplement industry. But there are two main reasons why diets never tend to live up to their expectations, especially as you get closer to your goal weight:
1Traditional diets misrepresent the calories in/calories out equation.
We’ve all heard that 450g (1lb) of fat is roughly equal to 3,500 calories, so the traditional calorie-counting approach is to cut calories by 500–1,000 per day in order to lose 450–900g (1–2lb) per week. The trouble is, as you get slimmer you become lighter and that actually reduces the amount of calories you burn at rest (your basal metabolic rate). So, in traditional weight-loss plans, weight loss is initially rapid but tends to slow down over time, even if you maintain that original calorie deficit. This can be very demotivating.
2It’s sticking to your chosen approach that’s often the hard part.
Even if you get your calories exactly right, how boring does counting every calorie get? Demotivation – either as a result of not seeing the numbers on the scales going down as quickly as they were, or boredom – can lead to lapses, which slow down the rate of weight loss even further. When you go back to your old eating habits – surprise, surprise – you’ll gain all the weight back, and a little more, as a result of the natural dip in basal metabolic rate (calorie burn) caused by your initial weight loss.
HOW FASTING MAKES A DIFFERENCE
FASTING MAY BOOST METABOLIC RATE
You’re probably thinking, “If I start starving myself, won’t that be worse for my metabolism?” First of all, fasting is not starving yourself, and don’t worry that eating less often will damage your metabolism. Losing weight naturally slows your basal metabolic rate (the amount of calories you burn at rest) in proportion to the amount of weight you lose, no matter which method you use. This is because your daily energy (calorie) needs are directly related to your age, height, gender and weight, in particular your lean body mass (muscle). It doesn’t mean that eating more often will fire up your metabolism.
You’ll hear over and over again that after a night of sleep, your metabolism has ground to a halt and you need to eat breakfast to stoke your metabolic fire. The idea that “breakfast boosts metabolism” is simply not true – it hasn’t been backed up by research at all. The breakfast myth is based on the “thermic effect of food”. Around 10 percent of our calorie burn comes from the energy that we use to digest, absorb and assimilate the nutrients in our meals. Roughly speaking, if you eat a 350-calorie breakfast, you’ll burn 35 calories in the process. But notice that you’ve eaten 315 extra calories to burn that 35. No matter what time of day you eat, you’ll burn off around 10 percent of the calories in your food through the thermic effect of food. So, whether you eat your breakfast at 7am, 10am or never, if you eat roughly the same amount and types of food overall, its effect on your metabolism will be the same.
In fact, all the research on fasting seems to show that eating less often could actually boost your metabolic rate. In one British study conducted at the University of Nottingham, a two-day fast boosted participants’ resting metabolic rate by 3.6 percent. In another study by the same research group, 29 healthy men and women fasted for three days. After 12–36 hours, there was a significant increase in basal metabolic rate, which returned to normal after 72 hours. The exact mechanisms for why this happens aren’t clear.
FASTING INCREASES FAT BURN
What is clear is that more of the calories you use for fuel during fasting come from your fat stores. Scientists can estimate what proportion of your energy is coming from fats and carbohydrates by measuring the amount of oxygen inhaled and the amount of carbon dioxide exhaled in your breath. The higher the proportion of oxygen to carbon dioxide, the more fat you’re burning. As part of the same Nottingham study, findings proved that the proportion of energy obtained from fat rose progressively over 12–72 hours, until almost all the energy being used was coming from stored fat. This is incredible news really!
We’re so often told to “breakfast like a king, lunch like a prince and dine like a pauper” with a view to becoming healthy, wealthy and wise. This is usually explained by telling us that breakfast kick-starts the metabolism – but it turns out that eating breakfast doesn’t boost your fat-burning potential at all. In a small study on breakfast-eaters – published in the British Journal of Nutrition – a 700-calorie breakfast inhibited the use of fat for fuel throughout the day. Put simply, when we eat carbohydrates, we use it for fuel, and this prevents our bodies tapping into our stubborn stored fat. Constant grazing might be what’s keeping fat locked away in your belly, bum or thighs – and fasting is one way to release it.
FASTING MAINTAINS LEAN MUSCLE
The more muscle you have, the more calories you burn at rest. And before you say you don’t want big muscles, another way to put that is: the less muscle you lose as you drop in weight, the less your basal metabolic rate falls as you move toward your goal weight. (Remember, your basal metabolic rate is the rate at which you burn calories, so it’s really important in order to make staying in shape easier in the long term.) Besides, muscle takes up less room than fat. So, a person with good lean muscle mass will take a smaller dress size or use a narrower belt notch than someone who doesn’t have it.
Fasting is better than plain old calorie restriction when it comes to maintaining lean body mass. This is largely because fasting triggers the release of growth hormone (GH), which encourages your body to look for other fuel sources instead of attacking its muscle stores. This is thought to be a survival advantage – back when humans were hunter gatherers it wouldn’t have made sense for our muscle mass to reduce when food was scarce – we needed strong legs and arms to hunt down our dinner!
In one study carried out by researchers at Intermountain Medical Center in the USA, participants were asked to fast for 24 hours. During this time, GH levels rose by a whopping 1,300 percent in women and 2,000 percent in men.
Many other studies have investigated the effects of fasting on GH. Like other hormones, GH levels rise and fall throughout the day and night. They tend to be highest at the beginning of a good night’s sleep, when our stomachs are empty but our bodies are hard at work repairing in preparation for a new day. Larger or more frequent bursts of GH are released when we continue to fast and also when we take part in vigorous exercise.
GH acts by sending a signal to our fat cells to release some of their contents into the bloodstream. This enables us to use more fat for fuel, instead of burning mainly carbohydrates for energy. GH is also thought to maintain concentrations of another hormone, insulin-like growth factor (IGF-1), which helps our muscles to build more protein.
This is totally different to what happens when you simply cut calories without changing how often you eat. When you hear people saying you should eat little and often to maintain your blood glucose levels, what they’re telling you to do, in actual fact, is to avoid this state. This is because whenever you top up your blood glucose levels through eating, your body releases insulin to compensate, and GH levels never get a boost when insulin is around.
It’s important to note that more isn’t necessarily better when it comes to GH – what’s key is resetting the balance between GH release (which happens in the fasted state) and insulin release (which happens in the fed state, however small your meal) in order to stimulate fat loss without losing lean muscle. You never need to fear growing giant muscles as a result of fasting – GH is released in waves and goes back to normal levels quickly as soon as your body has released enough fat to burn.
As mentioned earlier, if you’re already slim, it’s especially important not to overdo it when fasting. Research published in the academic journal Obesity Research shows that within just two days of complete fasting, there’s a dramatic increase in the use of muscle for fuel in people who are already a healthy weight. This is because they have less fat available to burn overall. Perhaps the advice for people who are already svelte but who want to fast for health benefits is to fast little and often rather than to eat little and often.
FASTING PATTERNS GIVE YOU ENERGY WHEN YOU NEED IT
Alongside maintaining your muscle mass to reduce the dip in your metabolic rate that happens as you lose weight, fasting may help with stubborn weight in other ways.
There’s a theory that the reduction in calorie burn typically seen after following a calorie-restricted diet may be related more to changes in activity level than to basal metabolic rate. When you’re only eating, say, 1,200 calories day after day, it may be difficult to maintain the energy levels and motivation to exercise. But following an intermittent fasting pattern means that you can concentrate your workouts around the times when you’re eating. More energy means a tougher workout – and more calorie burn overall.
COMMON QUESTIONS AND ANSWERS
QIsn’t “not eating” dangerous?
AIt’s very important to establish that fasting is not starvation, which, of course, is dangerous. What I’m talking about is the health benefits of increasing the gaps between meals or eating less from time to time.
Some people who are fully signed up to the merry-go-round of traditional dieting will argue that not eating is likely to induce a low-blood-sugar or “hypo” episode. Feeling faint, clammy and unable to concentrate are typical symptoms, happily offset by a visit to the vending machine or, for the health-aware, a snack such as an oatcake or nuts and seeds. I’m not suggesting that snacking should be outlawed – most of the time, I’m more than happy to tuck right in. But fasting challenges the assertion that we can’t survive, or even thrive, without five mini-meals a day.
I accept that challenging the blood-sugar story isn’t going to win me any popularity prizes. However, the reality of what science is telling us today is that there’s no medical consensus on the concept of low blood sugar. The vast majority of us are perfectly capable of regulating our blood glucose level and, although we may feel ravenous between meals, going without food for a few hours won’t cause the blood glucose to plummet and, even if it does, our self-preserving mechanisms will kick into action long before we pass out. What this means is that insulin’s countermeasure, glucagon, will kick in, releasing those locked-up glucose stores into the blood and bringing the glucose level back within its normal range.
A few words of warning, though… Diabetic “hypos” are a different thing altogether, of course, and can be very dangerous, but they are drug-induced. For people diagnosed as diabetic but who are not yet on insulin medication, fasting has proved promising. In a year-long study on intermittent fasting, the group who fasted every other day stayed off diabetes medication for significantly longer.
QWon’t I feel light-headed and really hungry on a fast?
AYou might be worried that your blood sugar levels will dip too low between meals and that you’ll feel faint and weak. But when you’re not eating, other hormonal signals trigger your body to release glucose or make more. In one Swedish study by researchers at the Karolinska Institute, students who’d reported that they were sensitive to hypoglycaemia (low blood sugar) felt irritable and shaky during a 24-hour fast, but there was actually no difference in their blood sugar levels – it may all have been in their minds.
It’s true that your brain requires about 500 calories a day to keep the grey matter ticking over effectively. The brain’s preferred fuel is glucose, which your liver stores around 400 calories-worth of at a time. In a longer fast, the body is forced to increase its production of ketone bodies, which act as a glucose-substitute for your brain. But in the short term, so long as you eat well before and after your fasting period, your body is perfectly able to produce enough glucose to keep your brain happy.
QHang on a minute… My trainer told me that six small meals will fire up my metabolism and stop me feeling peckish. Who’s right?
AThis is one of those fitness and nutrition “truths” that has been repeated so many times, people are convinced that it’s a fact. In one small study at the US National Institute on Aging, researchers found that people who ate only one meal a day did tend to feel hungrier than those who ate three. But beyond eating three meals a day, meal frequency doesn’t seem to make a difference to hunger or appetite, so it comes down to what’s actually easiest for you. A study published by the International Journal of Obesity showed that people who are overweight tend to snack more often.
The truth is, you will feel hungry when fasting – there’s no getting away from that – but rather than a constant unsatisfied feeling, your hunger will come in waves. You’ll start to recognize the difference between physical and psychological hunger. And you’ll get to eat meals that are big enough to leave you feeling genuinely satisfied when you do eat.
QSurely after the fast is over, I’ll be tempted to binge?
ADr Krista Varady, from the University of Illinois in Chicago, has been studying alternate-day fasting (ADF), a form of intermittent fasting, for several years. Her research studies put people on a strict calorie limit every other day. For women, this provides 400–500 calories a day and for men 500–600 calories a day, which is all eaten at lunchtime. On the alternate “feed day” participants can eat as much as they want, with no restrictions.
After a day of partial fasting, it turns out that people rarely gorge themselves on the feed day. Participants in the study ate, on average, around 110 percent of their energy requirements, which means that over the two days their calorie intake was similar to what it would be on a traditional diet.
That’s why the outcomes on weight loss are similar – but wouldn’t you rather eat as much as you like every other day rather than constantly feel like you’re “on a diet”?
But watch out… a couple of recent studies by researchers at Cornell University in the USA and Imperial College, London, suggested that after a fast, people are more likely to reach for stodgy or fatty foods first, so make sure you follow the guidance in later chapters in order to ensure that all your nutritional bases are covered.
QCan fasting change my shape?
AFor many women, that last bit of surplus weight is carried around the hips and thighs and it simply won’t shift. To solve this problem I suggest looking to the true body professionals.
According to noted intermittent-fasting expert Martin Berkhan, there’s a good reason for this. All the cells in our body have “holes” in them known as receptors. To switch activity on and off in those cells, hormones or enzymes enter the receptors. Fat cells contain two types of receptor – beta 2 receptors, which are good at triggering fat burning, and alpha 2 receptors, which aren’t. Guess which is mostly found in the fat stores of your lower body? Yes, our hips and thighs have nine times more alpha 2 receptors than beta.
Fasting is the only thing that alters alpha 2 receptor expression in adults – when we’re fasting, the alpha 2 receptors are more likely to stay hidden. If you combine this with the fact that GH and catecholamines (hormones released by the adrenal glands) are particularly good at encouraging fat loss, then fasting is a way for your body to release the stubborn fat it retained while you were on traditional diets.
QWhat about belly fat?
AAll over the Internet you’ll see promises that you can get rid of belly fat in a matter of days by taking supplements. We all know that this is simply not true. Stubborn fat around the middle is linked to a number of factors – including stress, alcohol, lack of exercise and a diet high in refined carbohydrates.
Every time you eat something sweet or a refined carbohydrate such as biscuits or white bread, your blood sugar levels rise quickly, causing your pancreas to release the fat-storing hormone, insulin. If you spend the day going from sugary snack to sugary snack, and especially if you wash everything down with a couple of glasses of wine, your body ends up storing more of the calories you eat and you end up with that dreaded “muffin top”!
Stress + refined carbohydrates + alcohol = a recipe for belly fat, especially if you’re unlucky enough to be genetically predisposed to weight gain around the middle.
QHow does fasting help torch belly fat?
ATo burn belly fat, free fatty acids must first be released from your fat cells (this is called lipolysis) and moved into your bloodstream, then transferred into the mitochondria of muscle or organ cells, to be burned (a process known as beta-oxidation).
Glucagon (another pancreatic hormone that has pretty much an equal and opposite effect to insulin) rises around four to five hours after eating, once all the digested nutrients from your last meal have been stored or used up. The purpose of glucagon is to maintain a steady supply of glucose to the brain and red blood cells, which it achieves by breaking down stored carbohydrates and leftover protein fragments in the liver. It also activates hormone-sensitive lipase, which triggers the release of fat from the fat cells, allowing other cells to be fuelled by fat as opposed to glucose.
When you’re fasting, belly fat can be turned into energy to keep your organs working effectively and, for example, to provide power to the muscles that hold you upright, as well as fuelling muscle movement.
In contrast, when you’re constantly grazing, your body doesn’t need to release glucagon. Instead, the pancreas pumps out insulin, which also acts to maintain blood glucose levels within a narrow range. Insulin encourages the fat cells to keep their fat tightly locked up. Not only that, but any spare glucose that isn’t required for energy and cannot be stored can actually be converted into fat.
Simply put, the body burns more fat in a fasted state, whereas, in the fed state, insulin causes fat to be taken up into the fat cells around your tummy (and elsewhere) for storage.
In one study, carried out at the Beltsville Human Nutrition Research Center in the USA, where weight loss wasn’t even a planned outcome, cutting meals down to one per day compared to three per day (without restricting calorie intake), led to a 2kg (4lb 8oz) loss of body fat in eight weeks.
While no studies have been carried out specifically to investigate how fasting affects your waist circumference, it’s been observed that people with high levels of belly fat tend to have lower levels of growth hormone. So in theory it makes sense that fasting is a better way to reduce belly fat than traditional dieting.
QWhat else can I do to help get rid of belly fat?
AEndurance exercise selectively reduces abdominal fat and aids maintenance of lean body mass, so it’s great to do in combination with intermittent fasting. Choose a fasting method that will enable you to take regular exercise – gentle activity such as walking will help, but high-intensity training is even better.
Also, a very small recent study, carried out at the University of Oklahoma in the USA, found that quality protein intake was inversely associated with belly fat, so make sure you fuel up on lean proteins (which your fasting plans are rich in), when you are eating.
QWhat about losing that last 4.5kg (10lb)?
AThis is often the hardest weight to shift. Not only that, it tends to creep back over a matter of weeks after you’ve finally reached your target weight. A familiar story is the strict diet we follow to get into beach-body shape in time for a holiday: in all the years I’ve helped people to lose weight, I’ve lost count of the number of times I’ve heard people telling me that all their hard work was undone by two weeks of sun, sea and sangria!
Remember that losing weight is all about creating a calorie deficit. Here, fasting is acting in two different ways. First, fasting helps maintain calorie burn – so in theory you can eat more overall and still lose weight. Second, fasting might just be easier to stick to than a boring calorie-counting diet. And when it comes to beach bodies, remember that old saying “a change is as good as a rest”. If you’re bored of the approach you’ve taken to weight loss up to now, a short blast of fasting can help you achieve your goal weight without damaging your metabolism.
This is backed up by research. Most of the studies on intermittent fasting show that it can be just as effective for fat loss as traditional diets, but the studies are all designed differently so it’s difficult to say exactly which fasting approach will be the most effective for you. Scientific studies on intermittent fasting have shown varying results – from an average weight loss of a few kilos in the first few days, to 8 percent of body weight within eight weeks.
During the first few days of the fast you’ll generally lose weight quickly, which can feel very motivating, especially if the scales have been stuck for a while.
One thing to note is that your weight will fluctuate. At first, you’ll lose water (because stored glucose holds roughly four times its weight in water, and is quickly used up during a fast), and yesterday’s food should make its way through your digestive tract. Alongside this, you’ll lose some body fat. But the next day, you’ll gain weight via the new intake of water and food. Don’t worry! Over time, your average weight will fall. That’s why it’s important to limit weighing yourself to once or twice a week, and to be consistent in the time and day you use the scales.
WEIGHT-LOSS CASE STUDIES
In deciding to write this book, I was determined to make the science more real. Actions speak louder than words, and nothing gives more credence to the beneficial and gentle effects of fasting than hearing from people who’ve done it.
I’d used juice fasting with hundreds of people over the previous ten years and knew it could help kick-start weight loss as well as tackle troublesome health symptoms, but I was a relative newcomer to intermittent fasting. I’d seen the impressive before-and-after shots on fitness websites like Lean Gains, and read all the scientific studies, but I needed to know how intermittent fasting would work on ordinary men and women who were struggling to get rid of those last 4.5kg (10lb) or who wanted to shift stubborn fat around the middle.
Six members from my weight-loss website, who were at various stages of their weight-loss journeys, agreed to be my guinea pigs. The results were really impressive. In just six weeks, they lost an average of:
•5.6kg (12lb 8oz)
•7.4 percent of their body fat
•5.8cm (2.3in) from their waist – that’s a whole dress or trouser size!
Some of their stories appear below.
OVERCOMING A WEIGHT-LOSS PLATEAU
REAL-LIFE EXAMPLE
NAME: Karen McKay
AGE: 38
HEIGHT: 1.8m (5ft 3in)
WEIGHT BEFORE: 67.5kg (10st 10lb)
WEIGHT AFTER: 62.1kg (9st 12lb)
LOST: 5.4kg (12lb)
Self-confessed “huge eater” Karen had already lost over 6.3kg (1st) in two months by following my portion-controlled plans (based on three meals and two snacks a day). At the start of the trial, she weighed 67.5kg (10st 10lb) but was still 6.3kg (1st) away from her ultimate goal, and her weight had reached a plateau.
“I’d always half-heartedly been on a diet but when I couldn’t get into my work trousers after Christmas I decided it was time for a totally different approach. I liked Amanda’s really fresh approach to healthy eating. I was determined to stick to the plan, and very quickly I’d lost the first 10lb [4.5kg], although the weight losses were smaller after that.”
Karen continued to follow my healthy eating menus, but switched from five small meals a day to a 16/8 fasting pattern, in which she fasted from 8pm in the evening until 12pm the next day. This meant skipping breakfast and her usual morning snack, then having an early lunch and a more substantial afternoon snack than usual. She slipped up a few times over the six weeks, even giving in to the temptation of some chocolate Easter eggs, but she still overcame the weight-loss plateau and lost a steady 900g (2lb) a week.
“For me this diet has been totally life-changing. Before, it was all about white bread, eating on the hop and huge portions. I’ve had a couple of blips along the way but I’ve totally changed the way I eat. The most incredible thing is that I’ve even managed to get into a size 10! I couldn’t even get into a size 14 after Christmas. I still can’t quite believe it. But this is me now – I’m determined and, as long as the kids keep me running around after them the whole time, hopefully I can stay this way.”
Karen noticed that her appetite tends to fluctuate alongside her monthly cycle. Look out for information on this in the “Me Tarzan, You Jane” chapter (see pages 120–30), which explains why fasting may work slightly differently for men and women. As a result, Karen continued following the 16/8 fasting pattern after the trial ended, but began eating breakfast every day during the final week of her cycle to help satisfy cravings.
Six months later, Karen is still maintaining her weight loss.
FITTING WEIGHT LOSS AROUND A BUSY WORK SCHEDULE
REAL-LIFE EXAMPLE
NAME: Juli Glasgow
AGE: 24
HEIGHT: 1.5m (5ft)
WEIGHT BEFORE: 76.5kg (12st 2lb)
WEIGHT AFTER: 70.2kg (11st 2lb)
LOST: 6.3kg (14lb)
Juli had only just signed up to my weight-loss site when I started looking for volunteers. She had an ambitious weight-loss goal – aiming to lose more than 19kg (3st) overall – and wanted a weight-loss plan that would fit her busy working life.
Juli followed a 5/2 fasting pattern, which meant that she ate a balanced menu five days a week, including three meals and up to two snacks. On the other two days, she was restricted to a small evening meal, averaging around 500 calories. This meant that she could structure her fasting pattern around the days when she’d be busiest at work – it’s often easier to skip meals when you’re busy, and it takes away the temptation to run for the vending machine rather than sit down to a proper meal. We also agreed that Juli could have one day off a week, usually at the weekend, when she didn’t strictly follow my menu. It was this flexibility that most appealed to Juli:
“I find it so rewarding to have snacks off-plan on one day, and find it much easier to get back on plan 100 percent after. Everything is structured, and on a working day it’s so easy to follow.”
Despite these planned “lapses” through weekend socializing, Juli also lost weight steadily and was a third of the way toward her ultimate goal by the end of the six weeks. Not only that, more of the weight went from around her tummy than her upper body. Her waistline shrank by an amazing 7.6cm (3in) during the trial!
LOSING WEIGHT WHEN EXERCISE IS IMPOSSIBLE
REAL-LIFE EXAMPLE
NAME: Sinead O’Neill
AGE: 40
HEIGHT: 1.6m (5ft 4½in)
WEIGHT BEFORE: 68.5kg (10st 13lb)
WEIGHT AFTER: 63kg (10st)
LOST: 5.85kg (13lb)
Like Karen, Sinead had already lost almost 6.3kg (1st) when she began the trial. She was feeling very motivated to reach her goal weight – another 6.3kg (1st) away – in time for her 40th birthday, and was keen to avoid a weight-loss plateau. A fractured foot meant Sinead was unable to exercise, so the intermittent fasting plan appealed to her as an alternative way to accelerate weight loss.
“I found it really easy – I did six days of no breakfast, but incorporated the same number of calories into the rest of the day’s food and it really worked. I got to my goal weight by my birthday and was delighted to get into a size 12 dress (my husband’s reaction was incredible!) and I’ve also worn leggings again, which I never thought I would. The plan has given me incredible confidence and I have so much more energy now.”
Sinead soon recovered from her broken foot, and started back at her exercise classes with a new-found confidence.