Carbohydrate intake varies on the low carbohydrate weight loss diets. Some low carbohydrate diets restrict intake to less than 20 percent of a person's calories in the form of carbohydrates, other weight loss diets permit up to 40 percent. These are significantly lower than the current US government recommendations to consume about 50-55 percent of a diet to be carbohydrates. The US government is expected to reevaluate and publish new recommendations in 2005.
Fat intake varies as well on the low carbohydrate diets. Some low carbohydrate diets suggest 55-65 percent of calories be obtained from fat, while others suggest only 30 percent. This differs with US government recommendations to eat about 30 percent fat, and American Heart Association advice to consume a maximum of 30 percent fat. More controversially, some low carbohydrate diets actually suggest that animal fats may be eaten liberally along with vegetable oils. This diet advice contradicts the recommendations of most heart specialists.
Suggested protein intake in low carbohydrate diets ranges from 25 percent to 40 percent of the diet composition. This is in contrast to the US government guidelines of between 15-20 percent protein.
These carbohydrate to fat to protein percentages may even change on a given diet, depending on how long a person has been on the diet. Many low carbohydrate weight loss diets are divided into phases or time periods. Phase 1 typically permits only a minimum number of carbohydrates, Phases 2 and 3 are usually more generous. The variations in time periods is part of the ‘recipe' of the diet company.
Low carbohydrate weight loss diets seem to produce a range of weight loss and health benefits, although some results were negative or inconclusive. Several researchers indicated that more research was needed before any definitive conclusions about the weight and health effects of low carbohydrate weight loss diets could be reached.