Getty ImagesA buzzy British eating plan called the Fast Diet grabbed our attention when it jumped the pond to the United States this spring. The dietwhich involves cutting your calories two days a weekwas created by Dr. Michael Mosley, MBBS, a science journalist, and built on research suggesting that intermittent fasting (IF) can not only help people shed weight but also reduce their risk of heart disease and diabetes. While the concept of fasting for health benefits and weight control has been around for centuries (even Hippocrates recommended it!), it has been gaining momentum in recent months thanks to Dr. Mosley's book The FastDiet (as well as other expert-penned IF offerings, including The 2-Day Diet). Curious? Here is an exclusive excerpt of the bookalong with our own version of a 500-calorie day.
Why I created this plan, by Dr. Michael Mosley, MBBS
About 15 months ago when I was 55, I went for a medical checkup and had a nasty shock. I discovered that although I looked quite slim, I was actually a TOFI (thin on the outside, fat on the inside). Internal fat, also called visceral fat, is the most dangerous sort of fat because it wraps itself around your internal organs and puts you at increased risk of heart disease and diabetes. Blood tests showed I was a borderline diabetic and had a cholesterol score that was way too high. Obviously I was going to have to do something about this.
What convinced me to try intermittent fasting? Well, a large number of studies with animals and humans have shown that it's good for health and weight loss. One of the best-researched forms of intermittent fasting is alternate-day fasting, in which you cut calories every other day. I, however, found ADF too difficult to do on a regular basis.Instead I decided to cut my calories just two days a week. I started calling it the 5:2 Fast Diet because for five days a week I was eating normally, and for two days a week I limited myself to 600 calories a day.
After three months, I had lost 19 pounds (down from 187 to 168), and my body fat had dropped from 28 to 21 percent. I lost 3 inches around my waist and stopped snoring, which delighted my wife and quite possibly the neighbors. Even better, my diabetes and heart disease risks, as indicated by blood tests, improved in spectacular fashion. My wife, Clare, who is also a doctor, was impressed. She regularly sees overweight patients who have blood chemistry like mine had been, and she said none of the advice she gives them has had anything like the same effect.
The Fast Diet is different from other programs because you diet for just two days a week. On fast days you eat healthily, but around a quarter of what would be normal for someone of your gender (500 calories for women or 600 for men).
There are various ways to handle fast days; some people prefer to eat all their calories in one sitting, others split them between breakfast and dinner, and others have three small meals over the course of the day. You have to see what works for you. [Note from the editors of Health: We recommend dividing the calories into mini meals, as shown at right.]
How to choose the right food
Because you eat less than normal on a fast day, it's important that you choose foods that will keep you satisfied longer.
Aim for fare that's high in protein, rich in fiber and has a low glycemic index, since high-GI foods (like bread, potatoes and rice) are likely to make your blood sugar spike, then crash. The Fast Diet doesn't recommend boycotting carbs entirely or living permanently on a high-protein diet. But the combination of proteins and low-GI foods on a fast day are helpful weapons in keeping hunger at bay.
On your fast days, go for healthy options that are low in saturated fat, like steamed white fish, skinless chicken, low-fat dairy, shrimp, tuna, tofu and other plant-based proteins. Nuts, seeds and legumes (beans, peas and lentils) have lots of fiber to fill you up (nuts may be high-calorie, but they're generally low-GI and satiating). 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 90 calories each, so an egg-based breakfast on a fast day makes perfect sense; poach or boil them to save on calories. Two eggs plus a 1Â¾-ounce serving of smoked salmon clocks in at a sensible 250 calories.