EAT, FAST AND PERFORM BETTER
CAN FASTING GIVE YOU A YOUNGER BRAIN?
The potential benefits of fasting go beyond weight loss and physical health. If you’ve ever found yourself befuddled about where you could possibly have left your keys/phone/purse/marbles, you’ll know that memory loss is a very frightening thing. The threat of long-term conditions like Alzheimer’s is arguably one of the most worrying aspects of ageing. But there is hope. Researchers at the National Institute on Aging in Baltimore have found evidence that fasting for one or two days each week may help protect the brain against Alzheimer’s, Parkinson’s and other brain diseases.
ISN’T BREAKFAST IMPORTANT “BRAIN FOOD”?
Children who eat breakfast tend to perform better in cognitive tests, but this doesn’t seem to be the case for adults. Studies have shown that short-term food reduction doesn’t actually impair cognitive function in adults. Prolonged dieting, on the other hand, does. This means that the perceived deterioration in brain function may, in fact, have a psychological cause – rather than being caused by a dip in blood sugar, lack of concentration may be a result of the stress of being “on a diet” (the way it tends to make you feel grumpy, miserable, and obsessive about food). Of course, it’s true that the brain uses glucose for fuel, but as we’ve seen in previous chapters, our bodies have enough stored glucose to see us through a short fast.
In one study, published in the American Journal of Clinical Nutrition, scientists observed that fasting and non-fasting groups of adults performed similarly in cognitive tests, even after two days without food. This is thought to relate to adaptive mechanisms – as adults, when we don’t have food available, it’s important that we have the mental clarity to go out and find it. Our hunter-gatherer ancestors didn’t have the option to pop out to the supermarket to grab a snack, and those who could think more clearly when hungry were more likely to be able to find food or outsmart predators. This was a survival advantage, and so the genetic factors that maintained cognitive function when food was scarce were passed on. As there haven’t been dramatic changes in our genes since caveman times, it makes sense that the ability to think clearly when we haven’t eaten for a while should still be the norm.
FASTING AND BRAIN HEALTH
Professor Mark Mattson, a renowned researcher at the National Institute on Aging, has dedicated his career to studying the effects of fasting on brain ageing. Until now, all his research has been on mice, but there’s now enough evidence of the beneficial effects of fasting on the brains of mice to begin research on humans.
At the National Institute on Aging, mice have been bred to develop a susceptibility to Alzheimer’s disease. If they are then put on a “fast food” diet which is high in sugar, they experience an earlier onset of learning and memory problems. But if they’re made to fast every other day, they find it much easier to remember their way around a maze. Brain scans on the mice show that fasting actually encourages new brain cells (neurons) to form by placing a mild level of stress on the brain cells, which encourages them to build up a resistance to future stress, as well as building new proteins. Other researchers have found that fasting also increases the rate of autophagy in the brain, thereby getting rid of any damaged “grey matter” and making way for healthy new cells. So, while it’s too early to tell whether fasting is the miracle cure for memory loss and age-related brain diseases, the research definitely sounds promising.
WHAT ELSE CAN I DO TO KEEP MY BRAIN YOUNG?
Sadly, the exact reasons why some people are susceptible to diseases such as Alzheimer’s are unclear. It’s generally accepted that diets rich in fruit, vegetables and healthy fats from fish, avocados and olives (typically like the Mediterranean diet) are associated with good brain health. What’s good for the body is also good for the brain!
One of the most important things that you can do for your body and brain is to get active and regular fasting might just help you do that. Recent studies published in the Archives of Internal Medicine indicate that the more active we are as we get older – even if it’s just gentle walking – the longer our brains will stay healthy. It sounds like the recipe for a healthy brain could be fasting combined with an active lifestyle and a real-food based diet – just what I have in mind!
CAN FASTING MAKE YOU FASTER?
I have to declare an interest here… For a few years I’ve loved the release that running has given me, especially after having my second baby. In fact, I’ve been a competitive soul from day dot. In my early youth I was good at badminton and represented Scotland in the game. In those days, not much attention was paid to sports nutrition, and since badminton is a largely anaerobic discipline it was possible to get by without thinking too much about what you were eating. Now, of course, everything has changed. Nutritionists feature large in all serious sport – not least, I imagine, because the “quick fix” route of banned substances has come under the spotlight, and, of course, we’re all more aware of nutrition’s role in exercise.
My running has become something of a “fix” – a means of releasing tension, either before the stress of the school run, or after the stress of a day’s work. My usual preparation used to consist of an espresso and a mostly empty stomach. While that works for a quick half-hour run, it was only when I stepped up to training for the London Marathon in 2011 that I became more scientific and observant of my nutritional requirements. I also wondered whether fasting during training or pre-event could make a person run faster.
COMMON QUESTIONS AND ANSWERS
QWhat’s the truth about sports drinks?
AIf you’re a keen runner or cyclist, or harbour ambitions to run a marathon, you’re probably aware of the importance of getting plenty of carbs. It’s impossible to open up a running magazine or take part in a race without being bombarded with adverts for the latest energy drink or gel.
It’s a fact that topping up your fuel levels with sugar – whether from fruit juice, sweets or expensive sports drinks – can make you run faster if your existing energy levels are low. Countless sports nutrition studies confirm that they do benefit performance. And the British public are buying into the dream en masse. In 2010, we drank 600 million litres of energy drinks and sports drinks.
However, topping up your blood sugar during exercise is only beneficial if you’re taking part in high-intensity exercise that lasts for more than an hour, such as running a half-marathon or competing in a football match. In other cases, it won’t do you any favours at all.
QWhat about fasting and exercise during Ramadan?
AInterest in the effects of fasting on fitness has increased in recent years, inspired by studies on what happens to Muslim athletes during the month of Ramadan. During Ramadan, Muslims are required to observe a period of fasting from dawn until sunset. This includes avoiding not only food, but fluids too. As the dates of Ramadan change from year to year, this means that it can take place across major events in the sporting calendar, such as the 2012 Olympics. If you believe the sports nutrition adverts, you may think that not being able to eat or drink regularly would ruin an athlete’s chances of winning, but that doesn’t necessarily seem to be the case.
While most medal contenders at the 2012 Olympics seem to have taken the opportunity to postpone their fast until later in the year, in 1980 Tanzanian runner Suleiman Nyambui won silver in the 5,000 metres while observing the Ramadan fast. The effects of fasting on athletes’ ability to compete and train during Ramadan are mixed. Several studies summarizing the research were published in the Journal of Sports Science in 2012. The overall picture was that the effects of fasting on performance are minimal, so long as overall nutritional intake and other factors, such as quality of sleep, are maintained.
Nevertheless, training while fasting – especially in the case of Ramadan, where athletes are also likely to be dehydrated through avoiding water – may make you feel more tired or reduce the amount of effort that you’re able to put in. But, for mere mortals rather than Olympians, intermittent fasting has the promising ability to improve overall fitness or sports performance.
QShould I cut carbs?
AAs mentioned at the beginning of this chapter, the roots of how fasting may benefit performance are in our evolutionary past. Our caveman ancestors simply didn’t have the opportunity to fuel up with carbohydrates before they went off to forage and hunt. Cycles of feast and famine meant that the ability to perform extended periods of physical activity on an empty stomach was an advantage when it came to survival. It’s thought that our genetic make-up hasn’t changed much in the 10,000 or so years since. So it makes sense, in theory, that humans are designed to exercise without taking on extra fuel.
At all times, our bodies burn both fat and carbohydrate for energy. While our storage capacity for carbohydrate is limited to around 500 calories-worth, most of us have more than enough fat stores to keep us going for a while. Say you’re 70kg (11st) and your body fat is 25 percent – that means you have over 150,000 calories of fat in storage.
Aerobic training increases the proportion of fat to carbohydrate burned, making it easier to exercise for long periods of time. Just as the body adapts to any training stimulus by getting stronger or fitter, the idea is that training when fasting – when stored carbohydrate levels are low – stimulates the body to become even more efficient at using stored fat for fuel. While it might therefore seem like a no-brainer that exercising without extra carbohydrate will help your body adapt, it has long been recommended that endurance athletes consume a carbohydrate-rich diet.
Carbohydrate is stored in muscles as glycogen, where it can easily be broken down into glucose to fuel movement. Most research continues to emphasize the importance of adequate carbohydrate intake, before, during and after exercise. This is particularly important during high-intensity events, where glucose is the main fuel – stored fat is pretty good at fuelling slow and steady movement, but it’s glucose that your body turns to when you want to move fast. In events or training that last over an hour, it’s generally recommended that 30–60g (1–2¼oz) of carbohydrate is consumed per hour, in the form of drinks, gels or food.
The mistake that many of us make is to rely on topping up our carbohydrate stores too much. This could also be the reason why many people don’t lose weight when they start exercising. A typical bottle of sports drink can take half an hour of leisurely cycling to burn off, so if that’s all you manage, and you add in a post-workout snack too, you could even find yourself gaining weight!
QWhat happens when you train while fasting?
ALooking back to a study carried out by the US Army in 1988, there’s no need to fear running out of glucose if you haven’t eaten for a day. In fact, it seems to be possible to exercise for just as long after a three-and-a-half day-fast as it is after an overnight fast when working at a low intensity. Researchers in the same study found that blood glucose levels were maintained too.
In another small study published in the Journal of Physical Activity and Health, this time on healthy people who exercised at a relatively high intensity for an hour-and-a-half, fasting for 16–18 hours didn’t impede their efforts. Interestingly, drinking a sports drink didn’t make them feel or perform better either.
Meanwhile, researchers at Pennington Biomedical Research Center have discovered that consuming carbohydrates during exercise can actually decrease the expression of genes that are involved in fat metabolism. So, the more carbs you take in during exercise, the worse your body gets at tapping into its fat stores!
Sticking to plain water, or a calorie-free drink, increases the proportion of fat burned during exercise because less glucose is available. When you consume a sports drink, the glucose is rapidly delivered to your blood and provides an instant source of fuel. Without this, you need to tap into your body’s fat stores.
Research by the University of Glasgow, involving 22 recreationally active males, showed that, in a one-hour cycling test after an overnight fast, those who drank a calorie-free drink burned 41 percent more fat than those who consumed a standard sports drink. It’s important to note that total energy expenditure was similar between the groups but, when thinking about weight loss, it’s the total amount of calories you burn that’s important. Those who drank the sports drink consumed around 250 extra calories, almost half of what they expended. If weight loss is a goal, there’s no need to take in this extra fuel during an hour of exercise.
And in another study on cyclists, published in the Journal of Strength and Conditioning Research in 2009, the combination of calorie restriction and exercising while fasting led to improvements in power-to-weight ratio (the amount of power you can produce relative to your body weight) without harming performance.
Even if you’re not a keen cyclist or runner and are just looking to lose weight, getting active first thing in the morning before your breakfast could be beneficial. Research published in the British Journal of Nutrition showed that overweight men who walked for an hour before eating breakfast burned more fat than those who ate first. It wasn’t a huge amount – an average of around an extra five grams – but that could add up over time.
QWhat’s meant by “train low, race high”?
A“Train low” means that some training is done without carbs to encourage the body to burn fat. As the bulk of modern sports nutrition research highlights the role of carbohydrates in enhancing performance under race conditions, the “race high” part involves taking on standard sports drinks or gels during events.
“Train low” training is different from simply training after an overnight fast, when muscle glycogen levels are still relatively high. Studies investigating the “train low” approach deplete participants’ glycogen stores by putting them through an hour or more of aerobic training. After an hour’s rest, participants then complete up to an hour of high-intensity exercise, all with only water to drink.
A recent study published in Medicine & Science in Sports & Exercise, involving 14 well-trained cyclists, showed that three weeks of high-intensity training in this glycogen-depleted state was as effective in improving time-trial performance as training with normal glycogen levels, even though power output during training was lower. Low-glycogen training led to a greater increase in the rate of fat oxidation by increasing the levels of enzymes involved in the metabolism of fat. At the same time, it led to greater resting levels of muscle glycogen after training. What this means is that, although training with low levels of glycogen (carbohydrate) in the muscles reduced the intensity the cyclists were able to work at during training, their race performance still improved. This is likely to be because the cyclists’ muscles responded to training with low fuel levels by storing more carbohydrate at rest and becoming more efficient at burning their fat stores for fuel.
Another study published in the European Journal of Applied Physiology found that a factor involved in muscle synthesis was reactivated more quickly after slow and steady endurance training in the fasted state compared to in the fed state in men.
Interestingly, most studies on low-glycogen training have been carried out on males. Energy metabolism during exercise varies between genders. A study published in Journal of Science and Medicine and Sport observed a greater increase in fat metabolizing enzymes for women when they trained in the fed state, suggesting that “train low, race high” may be more appropriate for men than women.
While there’s no clear evidence that the “train low, race high” approach will benefit performance, it’s worth experimenting with if you want to lose fat and get faster. Fitness training is about adaptation and not necessarily performing your best. By doing some high-intensity training in a fasted state you may be able to increase the level of fat-metabolizing enzymes in your muscles, meaning that you can work at a higher effort level without taking in extra carbs when racing.
All-in-all, this suggests that taking part in aerobic exercise while you’re fasting should not harm your body and may even help your body adapt to training at higher intensities without relying on sports drinks for fuel. This is an especially good thing if you’re a keen runner or cyclist and tend not to feel well when you take gels or energy drinks during a race.
But be careful because training in a glycogen-depleted state has its risks. These include increased levels of stress hormones, muscle breakdown, fatigue and lowered immune response. If, while fasting, you decide to add some endurance training to your schedule, especially at a high intensity, it’s probably best, initially, to limit it to once a week. Allow plenty of time for recovery, and monitor your response, stopping if you feel unwell or fatigued.
FASTING FOR A STRONGER BODY
Weight-training enthusiasts use intermittent fasting as a technique to build lean mass and lose fat, with the goal of achieving a “shredded” or “ripped” physique. The explosion in popularity of intermittent fasting over the past few years is in part due to fitness experts such as Martin Berkhan, who designed the “Lean Gains” 16/8 hour fast. This method focuses the fast around the times you’re scheduled to work out. The reason for this is that, in order to build muscle, you need to be in positive energy and protein balance after your workout, otherwise your muscles will be consumed for energy instead of getting bigger. Therefore, while the workout is done in the fasted state, the biggest meal of the day is right after the workout. Some people also take “branched-chain amino acid” supplements to maximize levels of growth hormone and to kick-start the muscle-building process.
The positive results posted on the Lean Gains website speak for themselves, but the technique is also backed up by scientific research. In one study, published in the European Journal of Applied Physiology, male participants grew more muscle when they did their weight training in a fasted state. This seemed to be facilitated by eating proteins and carbohydrates soon after training. Researchers concluded that fasting activated factors which stimulated muscle cell growth in response to the nutrients.
Going back to the discussion about what happens to people who exercise while fasting during the Islamic holy month of Ramadan (see pages 89–90), Tunisian researchers found that performing aerobic training in the fasted state led to greater fat loss. Although the study was very small, the results suggest that if you’re trying to shed body fat and hold on to your muscle, doing your aerobic exercise while fasting is the way to go. During the month-long study, participants who trained before eating lost a similar amount of weight to those who trained after eating. However, those who trained after eating did not lose as much fat, and therefore their body composition didn’t improve.
STRENGTH FOR WOMEN
Just because intermittent fasting was popularized by body builders doesn’t necessarily mean that resistance training in the fasted state will turn women into beefcakes. To gain significant amounts of muscle, you need to train hard – lifting progressively heavier weights several days a week – and eat more calories than you burn off. A strong, lean, toned look can still be very feminine, so do at least consider regular training with weights.
While fasting might help you become stronger, there is some evidence that it could also make you feel a bit wobbly! In a study by Canadian researchers, healthy young women who were asked to take part in balance trials were steadier on their feet after a meal than after a 12-hour fast. This may have implications for anyone who is worried about falling – if you’re exercising to build up muscle strength after an injury, for example.
FASTING AND MOTIVATION
The final motivator, when thinking about incorporating fasting with exercise, is that it could give you more energy to train. There are lots of arguments over whether diet or exercise is more important when it comes to losing weight.
You may be familiar with the saying “you can’t out-train a bad diet”. While it’s probably true that exercise alone isn’t going to get you the body you want if you pay no attention to what you eat, dieting without exercise isn’t a good idea either. After all, exercise comes with an impressive array of health benefits itself – from heart and lung health, to stress relief, to maintaining strong bones.
When it comes to muscle strength and the way you look, exercise is the clear winner over diet. Researchers at Ann Arbor University in Michigan looked at how women’s bodies responded to diet alone versus exercise alone. They found that, as expected, diet was more effective at reducing body weight, but exercise was more effective when it came to losing fat and maintaining muscle.
The thing is, getting the motivation to exercise can be hard when you’re “on a diet” because you’re always eating less than you’re burning off and you often feel like you just don’t have the energy. The good thing about fasting is that the gaps between meals are longer so when you do eat, you get to eat more. This means that you can time your exercise around the times when you’ve eaten and are feeling energetic. You’re more likely to work harder!
PERFORMANCE CASE STUDIES
REAL-LIFE EXAMPLE
NAME: Alex
Personal trainer Alex had always done a lot of weight training and eaten well, but in November 2011 he wanted find a method of eating that would help him strip away stubborn body fat.
“I first heard about fasting a number of years ago and wanted to do some more research and see how it could be implemented for body composition change. I had a look online to see how others had used it for the same goals. I run a tight food schedule anyway, but wasn’t getting the results I wanted. After immersing myself in the research on fasting, I decided to experiment with it. Everything I’d read indicated that it was a good way to trick the body into holding on to muscle at the same time as losing fat.”
For two months, Alex combined a strict high-protein, low-carbohydrate diet with fasting for between 16 and 20 hours a day. The aim of this was to reduce his body fat as quickly as possible.
“During this fat-loss phase, I lost 3kg [7lb] in weight – all of which was fat. I maintained my muscle mass, even though I was doing less cardio exercise than usual.”
Following on from this, Alex increased both his training and carbohydrate intake – first, to train for a rowing competition and then, for a strongman competition. His aims during these phases were to maintain a reduced body fat level, and still be prepared for competition.
Alex combined three weight-training sessions a week with two cardiovascular sessions. He took a conservative approach to increasing his cardiovascular exercise by using a heart rate monitor and slowly increasing his training sessions to 45–60 minutes. Generally he trained at midday, before his main meal, and on certain days he trained early in the morning, which left him feeling quite drained by mid-afternoon.
“I stuck to my plan rigidly most of the time. The only exceptions were at the weekend, when I sometimes had a few drinks. On Sundays, I usually had a ‘cheat’ meal too – a roast dinner and dessert! If anything, I think I possibly cut my calories too much in the early stages. When I started training for the rowing competition, my hunger levels spiked dramatically by the evening.”
To counteract these feelings of hunger and tiredness, Alex added some carbs after cardiovascular training – for example, a number of large bowls of porridge. To meet his calorie requirement, Alex found he was sometimes eating non-stop for an hour at a time!
Although Alex’s main aim was to increase strength and improve the way he looked, he performed better than he expected in the rowing competition. He also gained strength, finding that the amount of weight he could lift went up consistently week after week, which allowed him to place well in the strongman competition, too.
“The main benefit was that it brought me back in line with how much food I really need. The biggest strength of intermittent fasting is that it simply reduces your exposure to food. I like eating a lot when I do eat! I find that pairing intermittent fasting with low-carb food works best for me, although I suffer when I train in the early morning, and I experience an increased hunger for carbs after intense exercise. I still follow the 16–20-hour fast pattern most days but allow myself a relaxed day off on a Saturday, when I eat whatever I want to, but still keep it pretty clean.”
Alex’s main advice for anyone considering pairing intermittent fasting with intensive training would be:
•Stretch out the timescale – don’t try to lose fat too quickly.
•If you are cutting down on carbs, do this gradually to allow your metabolism time to adapt.
•Have your main meal immediately after training.
•Have a relaxed day off once a week.
NAME: Dana
Like Alex, Dana was used to training hard, and wanted to use fasting as a method of becoming very lean. She had been working out regularly for over two years and was already fit and toned but hoped that fasting would help her get rid of the last of her belly fat!
Dana followed a strict 20-hour fast, concentrating all of her meals in a small window between 1pm and 5pm.
“I usually stick to it very strictly, but sometimes I extend the eating time by an hour or two if I don’t get the chance to eat enough that day. Most of the time I find it hard to eat all my daily calories in only four hours. I usually break it into two main meals and a small snack if time allows. Another inconvenience is that I feel stuffed during the eating window and cannot train. I have to train only in the morning, on an empty stomach, because I feel lighter and can move better.”
Dana followed this pattern for three weeks, and during this time lost 2kg (4lb).
“I feel lighter, my stomach is flatter and I can see results in building lean muscle.”