By Ian K. Smith, M.D.

Reviewed by Elisa Zied, MS, RD, CDN

Claims

The 4 Day Diet claims to push your body to lose more weight because it varies the types and amounts of foods eaten as well as the kinds of exercise. Continually readjusting to new foods and exercises prevents the body from getting acclimated to any specific eating or exercise plan, which in turn will help to burn more calories and prevent plateaus.

Synopsis of the Diet Plan

The first part of the book is motivational, guiding readers to understand their food and fitness habits; encouraging them to keep a detailed food and fitness journal for 10 days; helping them set realistic goals (and continue to update and reevaluate them throughout the weight loss); and providing advice for staying motivated and resisting temptations that can undermine weight loss. Charts, questionnaires and mental exercises sprinkled throughout this part can help readers pay attention to their thoughts about their bodies, food and fitness.

The diet program is broken down into seven "modules," each lasting four days:

1. Induction (the detox or cleansing module)
2. Transition (all the food groups are reintroduced)
3. Protein Stretch (helps avoid plateaus)
4. Smooth (reintroduces some formerly "forbidden" foods)
5. Push (a more strict eating plan)
6. Pace (designed to help dieters "catch their breath")
7. Vigorous (helps lose those last few pounds)

Each module has its own specific diet plan and exercise recommendations. Readers are encouraged to begin with the first two modules in order (described below), after which they can follow any or all of the other five modules in whatever order they choose.

In the Induction module, the total daily calorie content varies considerably in the four days, from an estimated 1,000 calories or less to about 1,800 calories per day. Recommended foods include fruits, green leafy and other non-starchy vegetables, beans, brown rice and low-fat or nonfat yogurt or milk. No meats, poultry or fish are allowed and the only added fats are low-fat or nonfat salad dressing and a small amount of oil in a cabbage soup recipe.

The Transition module includes one set menu for the four-day period, providing approximately 1,300 calories per day. It recommends specific foods including fruits (apples, pears and berries), vegetables (carrots and cucumbers) and beans of your choice. Unlike the first module, the Transition module recommends fish, chicken or turkey, as well as two snacks (up to 150 calories each) from a list of about 50 options.

Nutritional Pros and Cons

A strength is the inclusion of both aerobic and strength-training exercise throughout the modules, although both types are not recommended in all the modules. Physical activity burns calories and possibly preserves lean muscle mass during weight loss.

However, there is no scientific support for the theory that varying calorie intake and exercise style will result in weight loss more than steady calorie reduction and increasing physical activity. In fact, according to the National Weight Control Registry, consistent eating and fitness behaviors are characteristic of people who successfully lose weight and keep it off.

The author also frequently refers to the Glycemic Index when discussing the types of foods recommended in the diet, but again, there is no evidence a G.I. diet causes significant weight loss or helps control appetite.

Furthermore, although many healthful foods are recommended throughout the modules, readers are at risk for consuming inadequate amounts of some nutrients. For example, most of the diet plan does not meet the 2005 Dietary Guidelines for Americans daily recommendations for whole grains or low-fat or nonfat dairy.

Finally, none of the meal plans, recipes or snacks includes any calorie or nutrient information. The author may spin this as relief from calorie counting, but long-term weight loss (and good health) generally includes learning what you are putting in your body.

Bottom line

Although there are many encouraging, healthful components to this diet, on some days it is too low in calories and skimps on key nutrients such as calcium and vitamin D. Following the modules may also prove to be quite cumbersome for some readers, while others may not respond well to the diet plan' restrictive inflexibility.

Could this diet help someone lose weight? Yes, just as with any diet that reduces calories and increases physical activity. But at the very least, readers who want to try this diet should adjust it to include adequate amounts of whole grains and low-fat or nonfat dairy each day and meet with a registered dietitian to meet their daily nutrient needs.