There are many drastic fad diets that promise to help you lose up to 10 lbs. in a week by making soup the basis of your diet. The Cabbage Soup Diet and the Sacred Heart Diet may be two of the better known plans, but other liquids-only diets include the master cleanse -- also known as the lemonade diet -- and the Mayo Clinic or grapefruit diet. Completely lacking in nutrition, these diets may do more harm than good in the long run. Discuss diets with your doctor first.
Soup diets, such as the cabbage soup diet, allow only the soup to be consumed for seven days. You can eat as much soup as you'd like, but nothing else. Other soup diets, such as the Sacred Heart Diet, allow for soup plus a specific combination of foods which change from day to day. One day you may be able to eat soup and additional vegetables; another day you can eat only soup, bananas and skim milk. Although these diets may claim weight loss occurs because of some fat-burning enzyme in cabbage or special combination of food, there is no medical evidence to back up that claim.
You will lose weight following a soup diet, but only because these plans are very low-calorie diets. If you drastically cut your caloric intake you will lose weight, especially for the first week. Any diet that restricts total caloric intake to 1,000 calories daily will cause weight loss. Unfortunately, due to the diuretic nature of these liquid diets, much of your weight loss will be water weight and will be easily regained as soon as you resume your normal eating habits. Additionally, you may experience low blood sugar and it's symptoms -- hunger, headache, fatigue, dizziness, anxiety or mood swings.
These fad diets are not safe nor nutritionally sound. They are too low in calories and lack vital nutrients including protein, healthy fat and fiber. Very low calorie diets often backfire by slowing your metabolism. The National Institutes of Health report that women need at least 1,200 calories and men need 1,500 calories every day to maintain metabolic function. Slowing your metabolism will eventually stall weight loss and actually make it easier to gain weight in the future. Because these diets are so low in protein, your body may convert lean muscle mass, rather than fat, to energy in the absence of readily available glucose. Losing muscle mass will also slow metabolism.
A lack of nutrients can compromise your immune system, leaving you open to illness or infection. Although the lack of fiber won't cause constipation while you're on the diet, because the diet is mostly liquid, when you break the diet, you may become constipated at the sudden increase of fiber in your diet that comes from eating real food again. These diets don't promote healthy lifestyle changes that could lead to long-term sustainable weight loss.