The Fast Diet: The secret of intermittent fasting � lose weight, stay healthy, live longer (7 page)

• Weight loss
  
 

• A reduction of IGF-1, which means that you are reducing your risk of a number of age-related diseases, such as cancer
  
 

• The switching-on of countless repair genes in response to this stressor
  
 

• Giving your pancreas a rest, which will boost the effectiveness of the insulin it produces in response to elevated blood glucose. Increased insulin sensitivity will reduce your risk of obesity, diabetes, heart disease and cognitive decline
  
 

• An overall enhancement in your mood and sense of wellbeing. This may be a consequence of your brain producing increased levels of neurotrophic factor, which will hopefully make you more cheerful, which in turn should make fasting more doable
  
 

So much for the science. In the next chapter Mimi discusses what to eat and how to go about starting life as an Intermittent Faster. How do you put the theory into practice?

T
here are, as we’ve seen, good clinical reasons to start Intermittent Fasting. Some, such as its positive effect on blood markers, should be immediately apparent; others will become manifest over time – a cognitive boost, a self-repairing physiology, a greater chance of a longer life. But perhaps the most compelling argument for many is the promise of swift and sustained weight loss, while still eating the foods you enjoy, most of the time. You may view this as incidental to the plan’s other marked health benefits. Or it may be your primary objective. The fact is you will gain both. Weight loss and better health, two sides of the same page.

Michael’s experience, as described in the previous chapter, will have given you an idea of what to expect. In this chapter I will reveal more detail – explaining how to start, how it will feel, how to keep going and how the central tenets of the Fast Diet can slip easily into the rhythm of your everyday life.

Now, it’s over to you.

Cutting calories to a quarter of your usual daily intake is a significant commitment, so don’t be surprised if your first fast day feels like a tough gig. As you progress, the fasts will become second nature and the initial sense of deprivation will diminish, particularly if you remain aware that tomorrow is another day – another day, in fact, when you can eat as you please.

Still, however you cut it, 500 or 600 calories is no picnic; it’s not even half a picnic. A large café latte can clock in at over 300 calories, more if you insist on cream, while your usual lunchtime sandwich might easily consume your entire allowance in one huge bite. So be smart. Spend your calories wisely – the Menu Plans on pages 139-161 will be useful – but it’s also worth having a clear idea of favourite fast-day foods that work for you. Remember to embrace variety: differing textures, punchy flavours, colour and crunch. Together, these things will keep your mouth entertained and stop it frowning at the hardship of it all.

Animal studies, human studies, research, experiment: as demonstrated in the previous chapter, evidence for the value of fasting is unequivocal. But what happens when
you step out of the laboratory and into real life? When and what you eat during your ‘fast’ is critical to the diet’s success. So what’s the optimal pattern?

Michael tried several different fasting regimes; the one he settled on as the most realistic and sustainable is a fast on two non-consecutive days each week, allowing 600 calories a day, split between breakfast and dinner. This pattern has been called, for obvious reasons, a 5:2 diet – five days off, two days on, which means that the majority of your time is spent gloriously free from calorie-counting. On a fast day, he’ll normally have breakfast with the family at around 7.30am and then aim to have dinner with them at 7.30pm, with nothing eaten in between. That way, he gets two 12-hour fasts in a day, and a happy family at the end of it.

The menu suggestions of pages 139-161 are based on this pattern as it is, in his experience, the most straightforward and convincing Intermittent Fasting method.

As will become clear later in this chapter, I found that a slightly different pattern works for me. Sticking to the Fast Diet’s central tenet, I eat 500 calories – but as two meals with a few snacks (an apple, some carrot sticks) in between, simply because the vast plain between breakfast and supper feels too great, too empty for comfort. There is evidence, from trials conducted by Dr Michelle Harvie
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and others, that this approach will help you lose weight, reduce your risk of breast cancer and increase insulin sensitivity.

Which approach is better? At this point, given that the science of Intermittent Fasting is still in its infancy, we don’t know. On purely theoretical grounds, a longer period without food (Michael’s pattern) might be expected to produce better results than one where you eat smaller amounts more frequently. Krista Varady and her team in Chicago have yet to run a study comparing people who consume their calories as a single meal with those who consume smaller meals throughout the day. They are not prepared to speculate on which is better. When we know more we will update you.

Professor Mark Mattson at the National Institute on Aging says that by eating your calories as a single meal you might get a modestly greater ketogenic (‘fat-burning’) effect, compared to three very small meals spread through the day. But he also thinks we shouldn’t get too hung up about it. ‘Regardless of whether the 600 calories is consumed as one meal or two or three smaller meals, you will get major health benefits.’

We await more trials but it is already clear from the hundreds who have tried it that as long as you stick to the Fast Diet you will enjoy that crucial combination of weight loss, health benefits and cheerful compliance.

Some people who don’t feel hungry at breakfast would rather eat later in the day. That’s fine. One of the key researchers in this field often starts her day with a late breakfast at around 11am and finishes with supper at 7pm. That way, she’s fasting for 16 hours a day, twice a
week. Based on the mouse study cited on page 28, it may even be a better approach.

It is, however, only better if you actually do it, and a delayed breakfast may not suit some lifestyles, timetables or bodies. So go with a timetable that suits you. Some fasters will appreciate the convenience and simplicity of a single 500- or 600-calorie meal, allowing them to ignore food entirely for most of the day. Whatever you choose, it must be your plan, your life. Do it with gusto, but be prepared to experiment, within the limits set out by the plan.

It may seem curious to talk about what to eat when you are fasting. But the Fast Diet is a modified programme, allowing 500 calories for a woman and 600 for a man on any given fast day, making the regime relatively comfortable and, above all, sustainable over the longterm. So, yes, you do get to eat on a fast day. But it matters what you choose.

There are two general principles that should govern what you eat and what you avoid on a fast day. Your aim is to have food that makes you feel satisfied, but stays firmly within the 500/600 calorie allowance – and the best options to achieve this are foods that are high in protein, and foods with a low glycaemic index (GI).
There have been a number of studies demonstrating that individuals who eat a diet higher in protein feel fuller for longer (indeed the main reason why people lose weight on diets like Atkins is because they eat less).
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The trouble with really high-protein diets, however, is that people tend to get bored of the food restrictions and give up.

There is also evidence that high-protein diets are associated with higher levels of chronic inflammation and IGF-1, which in turn are associated with increased risk of heart disease and cancer.
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So the Fast Diet does not recommend boycotting carbs entirely, or living permanently on a high-protein diet. However, on a fast day, the combination of proteins and foods with a low GI will be helpful weapons in keeping hunger at bay.

In earlier chapters, we discovered the importance of blood sugar and insulin. High levels of insulin brought about by high levels of blood sugar will encourage your body to store fat and increase your cancer risk. Another reason not to eat foods that make your blood sugar levels surge, particularly on your fast days, is that when your blood sugar crashes, as it inevitably will, you will start feeling very hungry indeed.

Carbohydrates have the biggest impact on blood sugars,
but not all carbs are equal. As habitual dieters will know, one way to discover which carbs cause a big spike and which don’t is to look at their GI. Each food gets a score out of 100, with a low score meaning that the particular food does not tend to cause a rapid rise in blood glucose. These are the ones you want.

The size of the sugar spike depends both on the food itself, and on how much of it you eat. For example, we tend to eat a lot more potatoes in one sitting than kiwi fruit. So there’s also a measure called GL, the Glycaemic Load, which:

GI x grams of carbohydrate
100

This makes some pretty heroic assumptions about the amount of a particular food you are likely to eat as a portion, but at least it is a guide.

The reason GI and GL are interesting is not just because they are strongly predictive of future health (people on a low GL diet have less risk of diabetes, heart disease and various cancers), but because there are so many surprises. Who would have imagined that eating a baked potato would have as big an impact on your blood glucose as eating a tablespoon of sugar?

Broadly speaking a GI over 50 or a GL over 20 is not good, and the lower both figures are the better. It is worth restating that GI and GL are measures that relate to carbs.
GI is not relevant to protein and fats, which is why none of the foods listed have a significant protein or fat content. As an example, let’s take a quick look at breakfast:

You can see why, if you are having a carb breakfast, porridge and muesli are better options than cornflakes or a croissant. And what are you going to put on your muesli?

The relatively high GI and GL of soy milk is just one reason to stick with dairy. And since we’re handing out surprises, here’s another one:

You would bet your house on ice cream being high GI/GL, but not so. If you factor it into your calorie count,
low-calorie
ice cream with strawberries is a treat to round off a meal. For more on the GI and GL of various foods and how best to plan your fast-day foods, see pages 107-8.

We certainly don’t recommend eating protein to the exclusion of all else on a fast day, but you do require an adequate quantity, for muscle health, cell maintenance, endocrinal regulation, immunity and energy. Protein is satiating too, so it’s well worth including it in your calorie quota. While Valter Longo recommends 0.8g of protein per kg of body weight per day – which would give a 12 stone man around 60g, and a nine-stone woman around 45g – perhaps the simplest method is to stick to recommended governmental guidelines, which allow for a (quite generous) 50g per day.

Go for ‘good protein’. Steamed white fish, for example, is low in saturated fats and rich in minerals. Choose skinless chicken over red meat; try low-fat dairy products over endless lattes; include prawns, tuna, tofu and other plant proteins. Nuts, seeds, pulses and legumes are full of fibre and act as bulking agents on a hungry day. Nuts – though high in calories (depending, of course, on how many you eat) – are generally low GI and brilliantly satiating. They
are fatty too, so you might imagine they are ‘bad for you’, yet the evidence is that nut consumers have lower rates of heart disease and diabetes than nut abstainers.
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Eggs, meanwhile, are low in saturated fat and full of nutritional value; they won’t adversely affect your cholesterol levels and they score a mere 85 calories each, so an egg-based breakfast on a fast day makes perfect sense. Two eggs plus a 50g serving of smoked salmon clocks in at a sensible 250 calories. Research recently found that individuals who consume egg protein for breakfast are more likely to feel full during the day than those whose breakfasts contain wheat protein.
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Poaching or boiling an egg avoids the addition of careless calories. Stand down the toast soldiers and replace with steamed asparagus spears. For more suggestions about foods to keep you full and fit on a fast day, and the benefits certain choices will bring, turn to page 107-8.