Diet Detective: How did you discover this diet — that is, using intermittent fasting?
Dr. Mosley: About 18 months ago, I went to have a routine physical, and my doctor told me that my blood tests had revealed I was a diabetic with a cholesterol level that was also far too high and would also require medication. This was a nasty shock, particularly as my father had died in his early 70s of complications of diabetes. I am 5 feet 11 inches and about 186 pounds, so I was not hugely overweight. I also eat quite well and am reasonably active.
I have never been on a diet, as I know most of them end in failure, and I also know that standard dieting has only modest effects when it comes to delaying the onset of diabetes. So I went looking for alternative approaches and came across researchers in the U.S. and the U.K. looking at intermittent fasting.
The idea is that instead of cutting your calories every day you cut your calories every other day, or perhaps only twice a week.
I tried different forms of intermittent fasting before settling on a version that I felt I could stick to. This consists of cutting your calories by one-fourth for two days a week. On a Monday and a Thursday, I would eat just 600 calories a day; for the other five days a week, I would eat normally. I called this the 5:2 Fast Diet.
On this diet, I lost 19 pounds of fat over three months, and all my blood levels returned to the normal range.
DD: The diet seems so simple. Is it really just eating normally five days a week and restricting calories (500 for women; 600 for men) the other two days?
DM: Yes, it is that simple. Actually doing it can be quite tough, particularly at the start. The foods you eat on your fasting days are also important as they should keep you full but also ensure maximum nutrition. I recommend protein (eggs, meat, fish) and lots of vegetables.
DD: Can you really eat whatever you want on the five unrestricted days?
DM: No, you can’t. If you overeat on the other five days, you will not lose weight or get benefits. Cutting your calories to one-fourth two days a week means you will cut your calorie intake by about 3,000 calories a week, which translates into around 1 pound of fat lost.
DD: Is there any validity to your critics’ claims that the diet is unhealthy and that it may be bad for the metabolism?
DM: There have been more than a dozen studies of intermittent fasting, following hundreds of men and women for periods of up to a year. These studies all suggest that intermittent fasting is safe and leads to greater improvements in key biomarkers, such as insulin sensitivity, than standard diets.
DD: Do you have a favorite healthy recipe?
DM: I love breakfast, and one of my favorite recipes is a mushroom and spinach frittata: eggs, mushrooms, spinach, and all for just 270 calories.
DD: What is your all-time favorite healthy snack?
DM: Humus with carrot sticks. If I am craving something sweeter it would be a small number of strawberries with a scattering of stevia, the natural sweetener that has no calories.
DD: What’s always in your fridge?
DM: Milk, eggs, butter, bacon and lots of vegetables.
DD: What did you have for breakfast this morning?
DM: I am in France at the moment, so I had a croissant and some cheese with a big mug of coffee.
DD: What is your favorite junk food?
DM: Hamburgers; I don’t need a lot of meat or cheese, but I do like relish and lots of flavor.
DD: What’s your favorite healthy ingredient? What’s the one thing you’d suggest people keep in their kitchen if they want to cook healthy meals?
DM: Garlic. It adds lots of delicious flavor, and the compounds in garlic are said to reduce fatty deposits. Plus, it keeps vampires at bay.
Charles Stuart Platkin is a nutrition and public health advocate and founder of DietDetective.com.