The three-day soup diet probably sounds pretty promising. You eat little or nothing but soup for three days and lose some weight -- up to 7 to 10 pounds. However, fad diets like the three-day soup diet generally don't work as advertised, according to the University of Cincinnati's NetWellness website. You'll probably lose some weight on the three-day soup diet, but you risk gaining it back almost immediately.
The three-day soup diet uses vegetable soup -- in most cases, cabbage soup -- as a meal replacement for the three days you're following the diet. You make the soup from scratch, using a head of cabbage, tomatoes, carrots and other vegetables and a base of canned broth or bouillon. In some versions of the three-day soup diet, you also can have skim milk and some fruit and vegetables, but in others you consume nothing but the soup for three days. Sugar, bread, pasta and soda all are banned. Some versions of the soup diet call for you to follow it for seven days instead of three.
You'll probably lose weight when following the three-day soup diet, since the soup contains few calories, according to the University of Florida. If you eat nothing but three bowls of cabbage and vegetable soup in one day, you'll probably consume only about 300 to 400 calories -- far less than your daily calorie requirement, which is probably around 2,000 to 2,200 calories. Therefore, you should be able to lose more than one pound of fat during your three-day soup diet.
Dieters using the three-day soup diet report much greater weight loss, but that's because they lose water and muscle mass on the diet, not fat, according to the University of Cincinnati's NetWellness website. It's simply not possible to lose multiple pounds of fat on a three-day diet. Once you end your diet, you'll regain the water weight quickly, and you also risk gaining additional weight because you will have slowed your body's metabolic rate, making it more difficult for you to lose weight and easier to gain it.
If you have no pre-existing health conditions, you probably won't harm your health by following the three-day soup diet, according to the University of Florida. The soup contains ample amounts of healthy vegetables and fiber, and potentially represents a healthy addition to your diet. However, if you have pre-existing high blood pressure, the sodium in the store-bought broth or bouillon soup base potentially can aggravate that condition.
Any diet claiming miraculous results probably doesn't work as advertised, according to the University of Colorado at Boulder. That goes for the three-day soup diet, as well. If you want to lose weight, your best bet is to make sustainable lifestyle changes, such as adopting a healthy diet and exercising more. In addition, you need to check with your physician prior to starting any weight loss diet, including the three-day soup diet, to make sure your body can handle it.