The Fast Diet: The secret of intermittent fasting � lose weight, stay healthy, live longer (12 page)

Clearly, men and women have metabolic and hormonal differences; for evolutionary reasons, we store and utilise fat in different ways. Women carry more fat, are better at storing it and tend to be more efficient at burning fat in response to exercise.
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Though few studies have been done, there’s some evidence to suggest that fasting women have a better response to endurance training than weight training,
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while men may fare better with weights. Anecdotally, men tend to find working out on an empty stomach easier to accomplish than women.

In terms of general health, the benefits of occasional,
short-term fasting for both sexes are pretty clear. Although quite a few studies have been done with male volunteers, others have been done with a mixed group or mainly female volunteers. Those in Krista Varady’s studies have been almost all women; Michelle Harvie’s volunteers, all women. Their results are striking and positive; nevertheless, further trials are required to analyse the precise effects of fasting on hormones, particularly among women of different ages. As with all recommendations in this book, be cautious and self-aware. This is not meant to be a struggle; it’s intended as a well-marked route to good health. If, for whatever reason, short bouts of fasting interrupt your cycle or your sleep pattern, modify your approach till you find a comfortable balance that works for you.

The science is still unfolding, and there haven’t been enough clinical trials to assess the overall effects of fasting on fertility. According to Professor Mark Mattson, an Intermittent Fasting plan, such as the Fast Diet, will not affect fertility. More extreme fasting may. It does in animals, but in a reversible manner. Nonetheless, we err on the side of caution and suggest that if you are trying to get pregnant, you should not fast. Period.

You should certainly not fast if you are already pregnant. Pregnant women should eat according to government guidelines and not limit their calorie intake.

There are certain groups for whom fasting is not advised. Type 1 diabetics are included in this list, along with anyone suffering from an eating disorder. If you are already extremely lean, do not fast. Children should never fast; they are still growing and should not be subject to nutritional stress of any type. If you have an underlying medical condition, visit your GP, as you would before embarking on any weight-loss regime.

If you do, it may be due to dehydration rather than a lack of calories. You might experience mild withdrawal symptoms from sugar (or caffeine if you’ve dropped it), but the brevity of your fast shouldn’t make this of particular concern. Keep drinking water. Treat a headache as you would normally; if fasting today is making you feel particularly unwell, stop. You are in charge.

If in reasonable good health, your body is a remarkably efficient and functional machine, capable of – in fact, designed for – the effective regulation of blood sugar. Short-term fasting is unlikely to yield a hypoglycaemic response. The recently propagated idea that we need to graze to avoid a ‘blood sugar crash’ is a myth; if you follow the guidelines set out here and eat low-GI foods on a fast day, your blood glucose should remain stable. But
don’t overdo it. If you fast for extended periods, longer than the bi-weekly, 24-hour modified eating programme recommended here, you may experience a drop in blood pressure, a drop in glucose levels and dizziness. So, fast smart. If you are diabetic, consult your doctor before embarking on any dietary change.

The Illinois researchers hypothesised that subjects would feel ‘less energetic on fast days, and would therefore be less physically active’.
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They found no such thing, which suggests that short-term, deliberate, modified fasting will not leave you beat. As in normal life, you’ll undoubtedly have up days and down days, good days and bad. Anecdotally, many Intermittent Fasters we have encountered report a boost in energy rather than a depletion. See how you fare. You may find that a fast day ends earlier than usual – no alcohol and plentiful sleep being a great way to arrive at breakfast sooner.

Probably not, though it will depend on your particular metabolism, and how you timed your fast-day calorie consumption. If you feel hungry, take your mind off it – a bubble bath, a good book, a stretch out, a herbal tea. Get psychology on your side: congratulate yourself on reaching the end of another fast day. Surprisiingly, perhaps, fasters report that they don’t wake up ravenous and run to the
fridge as soon as the alarm goes off. Hunger is a subtle beast, and your appetite will soon find its rhythm.

Since you’re not restricting calories every day, your body will not enter the fabled ‘starvation mode’. Your fasting will never be intense. It will only ever be conservative and short-lived, so while your body will burn energy from its fat stores, it will not consume muscle tissue. Research has shown that occasional fasting does not suppress the metabolism.
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Even extreme fasting – an absolute fast for three consecutive days
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or on every other day for three weeks
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– generates no decrease in basal metabolic rate. Nor does Intermittent Fasting raise levels of the hunger-stimulating hormone ghrelin. Researchers at Pennington Biomedical Research Center in Louisiana found that ‘ghrelin was unchanged in both the men and the women, even after 36 hours of fasting’.
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If you follow the moderate, judicious approach advised here, a short window without food is a scientifically sanctioned path to health and wellbeing.

Participate, but with a nonchalant awareness. While support from family and friends is an asset, making a song and dance about your fast will only cause you to feel self-conscious, turning the diet into an obstruction,
a hurdle, rather than something that should slot happily and calmly into your life. Remember your trump card: you’ll eat normally again tomorrow. Some days, of course, are tougher than others. As Dr Varady noted among her trial subjects, hunger spiked at week eight: ‘We speculate that this may have occurred because this study week corresponded to Memorial Day weekend, and subjects may have felt hungrier while attending food-related celebrations.’
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If you know that you have a social event – or a
food-related
celebration – in the diary, fast the day before or the day after. The flexibility of the plan explicitly means – in fact, it demands – that you still go to that wedding, birthday, anniversary dinner, christening, bar mitzvah, supper date, posh restaurant. Take a break for Christmas, Easter, Thanksgiving, Diwali. Yes, you may well put on a little weight, but this is a life, not a life sentence. You can always deviate, eat chips and dips and things on sticks, and then revert to more challenging fasting once the party’s over.

Clinical trials have concluded that Intermittent Fasting is a sustainable – indeed, one of the most effective – ways for obese individuals to lose weight and keep it off; the larger you are, the greater your initial weight loss is likely to be. If you are obese it’s likely that, for whatever reason, traditional restrictive diets have failed for you. The Fast
Diet is different because of its flexibility, its war on guilt, and its express approval of ‘pleasure foods’ on non-fast days. The Illinois studies have shown that obese people were able to quickly adapt to ADF. They were also able to maintain physical activity despite fasting. In conclusion, ‘overweight and obese patients appear to experience significant improvements with IF regimes’.
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As with any underlying medical condition, we recommend that you fast under supervision.

There’s no reason not to; that is, after all, what Dr Krista Varady’s ADFs (Alternate Day Fasters) effectively do. However, beware ‘fast fatigue’. One of the keys to its success is that the Fast Diet requires only short-lived dedication. Ask your body to do more than that and it may revolt and refuse to behave, making the recommended fasting programme harder to achieve. Experience tells us that two days is enough. But if you have a date and a small pair of party pants on standby, an occasional, single sneaky extra day shouldn’t hurt. Don’t, however, try a lengthy crash diet. Unless you are obese and it is medically supervised, it just isn’t worth it.

If you are already at a reasonable, happy weight, you can still fast effectively, but consider adapting your
consumption on non-fast days to encompass more
calorie-dense
foods. The main researchers we talked to in this field are all slim and they still fast. With practice, you will discover an amicable balance between fasting and feeding which keeps your weight in the prescribed range. Fast once a week, rather than twice a week. There have been no specific studies to illuminate the effects of doing this, but use your common sense and watch the scales; don’t slide. As mentioned above, if you are already extremely lean or suffering from an eating disorder, fasting of any description is not advised. If in doubt, see your GP.

On the contrary, there’s no time to lose. The Fast Diet is likely to prolong your life. It will moderate your appetite and help you lose weight. Its effects are quickly felt, often within a week of starting your simple bi-weekly mini fasts. It all points to a healthier, leaner, longer old age, fewer doctors’ appointments, more energy, greater resistance to disease. Our advice? Start yesterday.

Interestingly, the Fast Diet’s on/off eating scheme looks a lot like the approach of many naturally slim people. Some days they’ll pick, other days they’ll tuck into treats. In the long run, this is how the Fast Diet goes. As you settle into the routine, you’ll naturally moderate your calorie intake on fast days and feed days, until the process is innate.
When you reach your target weight, you can change the frequency of your fast. Play with it. But don’t drift; stay alert. Your aim is a permanent life change, not a blip, not a fad, not a dinner-party chat. This is a long-distance route to sustained weight loss. Accept that it is something you will do, in a form that suits you, indefinitely. For as long as life.

Fasting, as we mentioned at the beginning of the book, has been practised for many thousands of years and yet science is only just starting to catch up. The first evidence of the long-term benefits of calorie restriction were found just over 80 years ago, when nutritionists working with rats at Cornell University in the US discovered that if you severely restrict the amount they eat, they live longer. Much longer.

Since then, the evidence has continued to mount that animals not only live longer, healthier lives if they are calorie-restricted, they also do so if they are intermittently starved. In recent years the research has moved on from rodents to humans and we are seeing the same patterns of improvement.

So where do we go from here? Professor Valter Longo, who has done so much pioneering work with IGF-1, is running a number of human trials in conjunction with
colleagues at the University of Southern California, looking at the impact of fasting on cancer. They have already demonstrated that fasting will cut your risk of developing cancer; now they want to see if fasting will also improve the efficacy of chemotherapy and radiotherapy.

Dr Krista Varady of the University of Illinois in Chicago has a number of projects planned. She has a trial running at the moment looking at how well people are able to tolerate ADF in the long run. This is critical research because the success or otherwise of a dietary intervention depends entirely on compliance. Will people stay on it? Last time we spoke, she was also bubbling with ideas for the future, including investigations into why people on ADF lose fat but don’t seem to lose significant muscle mass, and why people on ADF don’t seem to fully compensate for the calories they’ve missed by eating more on their feed days. She has many theories but needs more cold hard facts.

Professor Mark Mattson of the National Institute on Aging in Baltimore is adding all the time to the dozens of research papers he has already published on the effects of fasting and Intermittent Fasting on the brain. We are particularly interested to see the outcome of some of his current studies, which include looking further into what happens to the brains of volunteers when put on an Intermittent Fasting regime.

In addition, his team is looking at drug therapies, as they know that despite the benefits, many people may
not want to fast. So they are, for example, investigating a drug called Byetta, used for the treatment of diabetes, but which also seems to activate the production of BDNF (brain-derived neurotrophic factor). This in turn, as we’ve seen, seems to protect the brain against the ravages of ageing. The hope is that Byetta or a related drug will, if not prevent dementia, at least slow its progression significantly.