Three-Day Diet


There are a variety of three-day diets that circulate from person to person and on the Internet. They tend to promise weight loss of 10 lb. (4.5 kg) or more in just three days.


The origins of the three-day diet are unclear. Some people believe that they go back to the 1980s when these kinds of diets were faxed from person to person. Three-day diets go by many different names, including the fax diet, Army diet, Navy diet, Cleveland Clinic diet, and many others. Often they are just referred to as three-day diets. Although many versions of this diet are named after medical institutions, no medical institutions claim responsibility for or recommend these diets. Institutions such as the British Heart Foundation and the Cleveland Clinic have issued statements that they do not support the three-day diet.


There are many versions of the three-day diet in circulation. All of them promise significant weight loss in just three days, but there are many variations in what dieters may and may not eat during these three days. One diet calls for dieters to drink only water for the first day. On the second day dieters may eat fruit and drink only fruit juice, and on the third day dieters may eat only vegetables and drink only vegetable juice.

Sample meal plan

A common version of the diet is:




There are other versions of the three-day diet, with some specifying even more alternatives for the dieter, including an orange instead of grapefruit, cottage cheese instead of tuna, and various vegetable substitutions. Most versions tell dieters to use lemon, salt and pepper, mustard, vinegar, herbs, soy sauce, ketchup, Worcestershire sauce, and other seasonings to add flavoring to the food, but nothing containing fat, such as butter.

A condition defined as having a body mass index of 30 or greater.
Very low-calorie diet (VLCD)—
A term used by registered dietitians to classify weight-reduction diets that allow around 800 calories or fewer a day.


The three-day diet usually promises dieters that they will be able to lose ten pounds in three days if the diet is followed exactly. Often the diet claims that the combination of foods called for by the diet causes some kind of increased metabolism that will burn pounds of fat. It is never made clear exactly what kind of reaction this is supposed to be or how it is supposed to work. The three-day diets are intended to provide a dieter with extreme weight loss in a very short time and are not intended to change the dieters lifestyle or overall eating habits. Usually the diets go so far as to tell a dieter to eat whatever he or she was eating before the diet once the diet is over. No exercise recommendations are made with three-day diets. Weight loss is supposed to occur from increased metabolism and lowered calorie intake alone.


There are many benefits to weight loss if it achieved at a moderate pace through healthy eating and exercise. Three-day diets, however, are not considered moderate and do not include exercise or a well-balanced diet. Any weight lost on a three-day diet is likely to come from lost water weight and may be quickly regained once the diet is over.



There are some risks associated with any diet, but diets that severely limit calories or the variety of foods that dieters may eat tend to be more risky than well-balanced, moderately calorie-reduced diets. The body needs food from each of the food groups every day for good health. Drinking only fruit juices or eating a very limited variety of foods can make it nearly impossible for a dieter to get all of the nutrients required for good health.

The most common three-day diet requires dieters to eat only about 1,000 calories per day, with some versions consisting of as few as 700 calories per day. This is not enough for most people to maintain good health. A diet that contains fewer than 800 calories per day is considered a very low-calorie diet. Very low-calorie diets carry high risks of side effects, such as gallstones and cardiovascular problems. Very low-calorie diets are intended only for people who are experiencing significant medical problems due to obesity. These diets are carried out under the close supervision of physicians. They are not intended or safe for people to follow on their own.

Dieters who follow a three-day diet may find that any weight lost is gained back as soon as the diet is over, and may even find that more weight is gained than was lost. Maintaining a very low caloric intake slows down the metabolism because the body thinks that it is starving. When a normal number of calories are reintroduced into the diet, the body wants to store extra fat in case there is a period of starvation again. This natural defense mechanism of the body against starvation can cause dieters who alternatively eat very few calories and then return to normal eating to gain large amounts of fat over time, even while they are trying to diet. Very low-calorie diets may also result in binge eating once the diet is over.

Research and general acceptance

Three-day diets are not healthy nor effective for long-term weight loss. Experts suggest that anything that promises dieters 10 lb. (4.5 kg) of weight loss in three days is unlikely to be taking off fat. Instead, dieters are probably losing water weight, with minimal fat loss at most and some muscle mass lost through the reduced caloric intake.

The U.S. Department of Agriculture makes recommendations for a healthy diet in its MyPlate guidelines. MyPlate provides recommendations about how many servings of each food group are required daily for good health. These recommendations can be found at . The guidelines are more realistic than those of the three-day diet. Sustainable diets should not be extremely restrictive or extremely calorie reduced.


Many studies have shown that exercise and diet are more effective at producing weight loss when done together than when either is done alone. Three-day diets do not usually have any exercise recommendations. Instead, they generally claim that a combination of foods will “magically” melt away fat. This is a false assumption, and healthy weight loss plans should include both a diet and an exercise component. The U.S. Centers for Disease Control and Prevention recommends that adults get a minimum of 30 minutes of light-to-moderate exercise each day for good health.

See also Binge eating ; Calories ; Fad diets ; Gallstones ; Metabolism ; MyPlate ; Obesity ; Soy .



Jones, Keith. Diet and Nutrition Sourcebook. 5th ed. Detroit: Omnigraphics, 2016.

Robitaille, Francis P., ed. Diet Therapy Research Trends. New York: Nova Biomedical Books, 2007.


British Heart Foundation. “Healthy Eating.” (accessed March 12, 2018).

Tish Davidson, AM

  This information is not a tool for self-diagnosis or a substitute for professional care.