There are very few rules here. No weighing out matchbox-size portions of cheese. No measuring, fretting, or complicated equations. In a nutshell, the fast day meal mantra is: mostly plants and protein.
This is the basis of all of the recipes in this book. Okay, there’s a little fat, too, a few slow-burn carbs, perhaps a drop of dairy. But “mostly p&p” pretty much sums it up. The only other word we’d add is variety. A varied plate of food promises a diverse lineup of nutrients and will add interest to your day.
So what should be on your fast day plate?
One of the more important hormones determining your health is insulin. When you eat, particularly foods rich in carbohydrates, your blood sugar levels rise, and in response the pancreas churns out insulin. Insulin helps remove glucose from your blood and store it in your liver or muscles as glycogen. Insulin also stops your body from using fat as a fuel.
If you constantly eat lots of sugary, carbohydrate-rich foods (and drinks), your body copes by producing increasing amounts of insulin. In time, your cells become less responsive, and your body becomes caught in a vicious circle where it has to produce ever-higher levels of insulin to get the same result. This can lead to type 2 diabetes, which in turn significantly increases your risk of heart attack, stroke, impotence, blindness, and losing your extremities due to poor circulation. It is also associated with brain shrinkage and dementia.
An added problem is that as well as being a sugar and fat controller, insulin and a related hormone called IGF-1 (insulin-like growth factor 1) stimulate the growth and turnover of new cells. This constant activity increases the risk that some of these cells will turn cancerous. High levels of insulin and IGF-1 are associated with a range of cancers including breast, bowel, and prostate cancer.
There is good evidence that restricting your calorie intake, and in particular your carbohydrate intake, for a couple of days a week will improve insulin sensitivity and cut levels of circulating insulin. The recipes in this book are based on that approach, referencing the glycemic index (GI) and glycemic load (GL) of the ingredients. You’ll recall that the GI rating measures the effect of a food on blood sugar relative to pure glucose (which scores 100). The GL takes into account how much carbohydrate is in a food. Watermelon, for example, has a high GI but a relatively low GL, as it’s mostly water.
On the days when you are fasting, you still eat, but you should aim to eat foods with a low glycemic index; in other words, foods that do not cause spikes in blood sugar. Most vegetables are a FastDieter’s friend because they have a low GI, and also because they provide a lot of bulk for very few calories, keeping hunger at bay.
Unlike fast-release carbohydrates, protein keeps you feeling full for longer, which is one reason to have plenty of it in fast day meals.
When people see the word protein they generally think of meat. Though chicken and beef are rich in protein, there is also protein in fish, milk, nuts, seeds, and legumes. Proteins are essential nutrients, the building blocks of your body tissue as well as a major fuel source. Unlike fat or carbohydrates, protein is not stored by your body; instead, food containing protein is broken down by your digestive system to provide amino acids, which are then used for a whole range of vital activities, from building muscle to creating hormones, enzymes, and neurotransmitters.
Because your body does not store protein, we recommend that you boost the protein content of your diet on fast days so that it becomes a greater proportion of your daily diet on just those days. That way, you benefit from its satiating effects (protein really does make you feel fuller for longer than carbs) and you will have adequate levels of protein at all times. On nonfasting days, of course, we recommend that you eat as usual and don’t concern yourself with dieting.
The recommended daily level for protein is roughly 55 grams. If you want to be more precise, one guideline suggests 0.83 gram per kilogram (2.2 pounds) of body weight, which for a 154-pound (70-kilogram) man works out to about 58 grams a day, and for a 132-pound (60-kilogram) woman, to about 50 grams.
The pigments that plants produce don’t simply attract pollinating insects; they represent some of the thousands of bioactive compounds, known as phytochemicals, that keep plants alive and healthy. By eating a wide range of different-colored plants, we also get those benefits, and on a fast day, they are the central event.
“Leafy greens,” which include spinach, chard, lettuce, and kale, are a good source of minerals such as magnesium, manganese, and potassium. Another class of green vegetables, the cruciferous ones, are those that contain sulfur and organosulfur compounds. These include cabbage, cauliflower, broccoli, and other members of the Brassica family. Sulfur is essential for the production of glutathione, an important antioxidant, as well as amino acids such as methionine and taurine.
Different vegetables will bring different things to your plate. Spinach, for example, contains lots of calcium, but not in a form that the body can readily absorb; if you want calcium, you are better off with broccoli. You can learn more from the Nutritional Bonus (NB) included with most recipes in this book.
Flavonoid comes from the Latin word flavus, meaning yellow, and in a plant this substance attracts insects for pollination and protects against harmful ultraviolet light. In humans there is some evidence that eating flavonoids helps combat the risks of allergy, inflammation, and infection.1 Fruits and vegetables with a significant amount of yellow or orange, such as carrots, melons, tomatoes, peppers, and squash, contain a particular type of flavonoid called carotenoid. The type of carotenoid in carrots can be converted to retinol, an active form of vitamin A, important for healthy eyesight, bone growth, and regulation of the immune system.
There are a huge number of carotenoids with different properties. One other class, called lycopene, produces the color red. You’ll find lots of lycopene in tomatoes. It is an antioxidant and a recent study showed it helps reduce the risk of having a stroke.2 Oddly enough, cooking tomatoes boosts the levels of lycopene, because heat helps break down the plant’s thick cell walls, making the nutrient more available for absorption.3 Unfortunately, heat also destroys vitamin C, so it’s a trade-off.
Blue and purple foods get their color from a group of flavonoids called anthocyanins. You’ll find decent levels in blackberries, blueberries, purple carrots, and red cabbage. There is some evidence that anthocyanin-rich blueberries may slow the rate at which memory and cognitive function decline as people age.4
Examples include garlic, white onions, shallots, and leeks, all rich in allyl sulfur compounds. Although there is no compelling proof that garlic will ward off vampires, it does appear to be quite good at killing microorganisms; traditionally, it has been eaten raw to treat coughs, colds, and croup.
There is debate about the best way to cook vegetables in order to retain as much of their goodness as possible. The answer is . . . there is no single answer. It all depends.
The reason we cook food is to make it more digestible; cooking tenderizes meat and breaks down tough vegetable fiber, something our digestive systems can no longer really cope with. But cooking also affects certain vitamins. Vitamin C, for example, is fragile and easily lost when heated, whereas lycopene is enhanced by the cooking process. If you live on a raw food diet, it’s likely that you will enjoy high levels of vitamin C but low levels of lycopene. Boiling and steaming carrots, spinach, and cabbage will also increase the bioavailability of carotene while reducing some other vitamin content. Our advice would be to mix up the raw and the cooked. Have both. Often.
When people are told they need to eat more fruit and vegetables, they frequently respond by simply eating more fruit. On the face of it, that’s not a bad thing as fruits, like vegetables, are packed with nutritional goodies. Unfortunately, many fruits are also packed with calories and fructose. Vegetables, by contrast, provide a lot of bulk and masses of fiber and have limited impact on your blood sugars and therefore on your insulin.
Some fruits, like strawberries and blueberries, have surprisingly few calories and do not adversely affect your blood sugar (unless, of course, you drench them in sugar), which is why you will find them in the recipes here. Black currants and raspberries do respectably well, too. Others, however, such as pineapple, are high in sugars. A large banana, for example, has about 120 calories, while a large carrot has more like 30 calories and a large serving of broccoli about the same. So while we would certainly encourage people to eat fruit, on fast days we recommend that sweet-tasting fruit be rationed.
If you do choose to eat fruit, make it fresh, not dried, as the drying process concentrates calories. A 31/2-ounce (100-gram) serving of fresh apricots, for instance, typically has about 31 calories while the same quantity of dried apricots clocks in at four times the calorie cost.
Although fruit is generally a nutritious option, juice is ultimately a higher-sugar, lower-nutrient version of its source. Juicing inevitably reduces or eliminates fruit and vegetable skin—yet those vital health-giving pigments, the seats of flavonoids and carotenoids, are concentrated in the skin and, in some cases, the pulp. Another case of your grandmother being right: eat the skin.
Plant skins are also the primary, if not the sole, source of fiber, important for the health of your gut—and also for slowing down the digestion and absorption of sugars. The take-home message is this: Juice can offer a decent source of nutrients on days when it’s hard to work in your usual amount of fruit and vegetables, but it’s not an adequate substitute for the real, whole source.
Fat matters, and there is such a thing as too little fat in the diet. This is because certain vitamins (A, D, E, and K) are fat soluble, which means that they require fat in order to be absorbed by the body (B vitamins and vitamin C are water soluble and don’t need fat for absorption). Essentially, dietary fat ferries vitamins across the cell walls of the small intestine, into the bloodstream, and on to the liver, where they are stored till the body needs them. But not all fats are equal. On a fast day, reduce saturated fats (animal fats), avoid trans fats, and instead choose plant fats from nuts, seeds, olives, or avocados. You need only a little, added to a vitamin-rich meal. The recipes in this book provide just that, so you don’t even have to do the math.
You’ll notice that there are plenty of recipes for soup here, and you may question their inclusion, given our advice on juicing fruit. Soups are a special case, and well worth including on a fast day menu. Research has shown that, while fluids generally have lower satiety value than solid foods, soups break the rule: They are brilliantly satiating, leading to what scientists at Purdue University call “reductions of hunger and increases of fullness . . . comparable to the solid foods.”5 In short, soup gets you full and keeps you there. Great news for a fast day. Better yet, a homemade soup uses up elderly vegetables from the fridge, never tastes the same twice, and will warm the cockles of your heart.
The timetable is largely your own. Eat when it suits you, your family, your lifestyle, your day. The recipes here are divided into breakfasts and suppers, but there’s no definitive reason to eat them at those times, other than that they mark a traditional start and end to a day. Many of these recipes work well as anytime meals, to suit the pattern that you have developed. You may wish to skip breakfast or dodge dinner. That it is entirely up to you. The FastDiet has been called the ultimate flexible diet with good reason.
It is, however, important to aim for as long a fasting window between bouts of eating as possible—this is where many of the health benefits of intermittent fasting lie, as readers of our first book will already know. On a fast day, Michael and I both have breakfast at 7:00 a.m. and supper at 7:00 p.m., giving us an ideal twelve-hour window. You may opt for something different. We are not dispensing rules, simply offering suggestions.
It’s worth revisiting these words from The FastDiet: “Your aim is to carve out a food-free breathing space for your body. Going to 510 calories (or 615 for a man) won’t hurt—it won’t obliterate a fast. Indeed, the idea of slashing calories to a quarter of your daily intake on a fast day is simply one that has been clinically proven to have systemic effects on the metabolism. While there’s no particular ‘magic’ to 500 or 600 calories, do try to stick to these numbers; you need clear parameters to make the strategy effective in the medium term.”
But the crucial thing is to find a way that works for you. Which means you may need to cope with feeling a little . . .
As many successful fasters now know, hunger is not the beast we imagine it to be; it is generally manageable and usually fairly modest, and the pangs soon pass. Of course, the whole idea of the FastDiet is to give your body an occasional break from eating, periods of “downtime” when it does not have to process food. Some people will find, after trying it for a few weeks, that they can comfortably go up to 12 hours without food. For others this will prove too challenging. The most important thing, remember, is finding a system that you can stick to.
That is why this book does suggest suitable snacks for your fast days (see Chapter 13). If you must snack, do it with awareness and frugality, avoid carbs, and always keep an eye on the GI. Remember, too, that any snacking will eat into your allotted calories—you will be eating the same number of calories, but they’ll be spread out over the course of the day. Does this undermine the benefits of intermittent fasting? We just don’t know; the studies have not been done. The important thing, in our view, is to not be put off or to give up at the first hurdle because you find the experience of fasting too difficult. If snacking helps you to start with, that is fine.
Of course, if you eat the right things on a fast day, it’s possible that you’ll escape hunger entirely. Time, then, to introduce the recipes and how the book works.