Most quick weight loss programs last a few days up to a maximum of two weeks. In either case, the duration of most quick weight loss diets is not long enough to do any permanent damage. If you remain on the diet longer than two weeks, however, you may develop nutritional deficiencies. Most quick weight loss programs are not balanced, so they can never satisfy all of your nutritional needs.

Quick weight loss programs focus on one or two types of foods and eliminate the rest. According to the American Heart Association, no one type of food has all the nutrients you need for good health. Take the cabbage soup diet for instance. Although the diet also includes fruit and other vegetables, it eliminates protein on most days. One day even calls for eating only bananas and skimmed milk.

Cabbage is packed with vitamin K and C, as well as dietary fiber, vitamin B6, calcium, and omega 3 fatty acids. You can get plenty of nutrients from cabbage but it lacks vitamin E, protein, carbs, and calories—all things the body needs for optimal functioning. You will lose large amounts of weight on the cabbage soup diet if you can last 2 weeks, but continue beyond the 2-week period and you will also lose energy and muscle, and your body will be missing out on the other vital vitamins and nutrients it needs to survive.

Quick weight loss diets like the cabbage soup diet are not designed to be a permanent weight loss solution. The cabbage soup diet is used to prepare overweight heart patients for surgery. During the seven days before surgery, patients typically lose 10-17 pounds. Keep in mind that most of the weight loss during the initial stages of any diet is usually only water weight.

Other quick weight loss diets or extreme low-calorie diets are used to help ease symptoms from certain conditions or jump start weight loss for overweight or obese patients. These programs are carefully monitored by physicians. This means patients are usually given prescription grade supplements to make up for vitamin and nutrient loss.

Scarsdale Diet fans might point to this diet and say that it’s balanced because it includes foods from all major food groups, but there’s only one problem–weight loss occurs at a average of 1-1.25 pounds per day, so this is also a quick weight loss diet. The rapid weight loss occurs as a result of severe calorie restriction. The diet averages around 800-1,000 calories per day. Because each individual’s calorie needs are different (even a 2-3 year old child requires 1,000+ calories per day for good health), 800-1,000 calories per day isn’t sufficient for the average adult. Remember, healthy weight loss occurs at a rate of 1-2 pounds per week, and calorie needs are based on age, height, weight, build, activity level, and any medical conditions.

The good news about quick weight loss programs is, they definitely work short-term. So if you plan to take a trip to a tropical island and you want to be bikini ready, or you want to slim down for a college reunion, or you’re getting married and want to look slim and trim in your wedding gown, a quick weight loss program might a temporary solution. If you need or want to lose weight, but you also want to keep it off permanently, a quick weight loss program just won’t work. Unfortunately, as soon as the diet ends, the weight will return.