The Fast Diet promises that a dieter can eat normally for five days of the week while picking two nonconsecutive days to limit calories to a quarter of normal intake (500 calories for women and 600 for men). On these fasting days, the dieter is encouraged to focus calories on a combination of lean protein and low-glycemic foods. The book includes 10 examples of daily fasting calorie menus, photos showing what a typical fasting meal looks like, charts outlining the glycemic index and load of various foods, and calorie content of typical foods.
While there is some emerging research that suggests intermittent fasting diets may help prevent disease, much more research is needed. Historically, fasting diets lead to increased calorie consumption on nonfasting days, which can thwart weight-loss efforts. Any variation of fasting may make a person irritable, cause daytime sleepiness or sleeplessness at night and can even lead to dehydration.
This book indirectly suggests that you can gorge on most days and then make up for it by starving yourself on other days, which is not a realistic long-term solution. It also does not complement other healthy lifestyle components like being physically active and getting quality sleep.