Type of food diets may claim that it is the amount of the high calorie foods that is causing the weight gain, and will advocate avoidance of food groups to some degree or another. While other types of food diets will advocate a low calorie food to be eaten, with or with out a quantity restriction. Their position may be that because it is a low calorie food, the amount is of less significance and essentially unlimited amount may be consumed.
It should be stressed that any significant and true weight loss will most likely occur when the diet is used for an extended period of time. If the time period is short, then the weight loss is most likely associated with water loss or the weight loss will be temporary.
Type of food group diet advocates may be further though of as advocates of not only a type of food but also how much of the food group. There seems to be advocates of all different combinations the food groups using exclusive or varying amounts of low carbohydrate, low fat, low protein, high carbohydrate, high fat, or high protein.