Many dieters use low-calorie diet plans in the simplest form, by setting a daily calorie limit and not eating more than that number of calories. Others may combine a low-calorie diet plan with another diet plan to maximize results. Some people who are desperate for quick weight loss may resort to diets with extremely low calorie limits, which are usually thought to be unhealthy by nutritionists and medical professionals.
Basic low-calorie diet plans restrict only calorie intake, without limiting the types of foods that may be eaten. In theory, a dieter with a 1,500 calorie limit could eat 1,500 calories worth of brownies and ice cream and still technically be following the diet plan. Many dieters, however, find that they are much less hungry if they eat a large volume of foods that are not calorie-dense, rather than a tiny piece of dessert food that is packed with calories. Additionally, it may be a good idea when following a low-calorie diet to take a daily multivitamin to prevent any vitamin deficiencies that may occur as a result of restricting food intake.
Some low-calorie diet plans might also focus on reducing intake of a specific type of food. This may be limited to one food group, such as when a dieter wishes to eliminate high-calorie desserts and sweet snacks from his or her diet. It may also extend to entire macronutrients, for example a low-fat or low-carbohydrate diet that also limits total calorie intake.
In addition to putting a limit on the maximum amount of calories a dieter eats, most nutritionists agree that there should also be a minimum number of calories that must be met each day. Restricting calories to an extremely low level can result in health problems, deficiencies, and a slowed metabolism. Extremely low-calorie diet plans, often warned against by nutritionists and doctors, include fruit diets, juice diets, and crash starvation diets.
Some people supplement a low-calorie diet plan with regular exercise to maximize weight loss. If the number of calories burned during exercise is significant, some dieters may add it to the daily calorie intake limit to avoid becoming fatigued on the diet. For example, a dieter sets her limit at 1,500 calories per day in order to achieve slow, steady weight loss at a healthy rate. If she burns 500 calories during exercise, she should then eat an additional 500 calories that day, for a total of 2,000 calories. If she does not do this, it would be the same as if she would have eaten 1,000 calories, which is generally considered too low for healthy weight loss.