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Dr. Atkins refers to this claim as the "metabolic advantage." In his book he states, "On a low-carbohydrate diet, there are metabolic advantages that will allow you to eat as many or more calories as you were eating before starting the diet and still begin losing pounds and inches."
There is no scientific evidence showing that low-carbohydrate ketogenic diets have a metabolic advantage over any other type of diet. In many studies comparing high-fat versus high-carbohydrate diets, it has been concluded that increasing fat content while holding energy constant does not increase energy expenditure. In fact, in several of the studies, those subjects on the higher carbohydrate diets had higher energy expenditure.7
No evidence exists stating that diet can break the "first law of thermodynamics." The first law of thermodynamics states "energy can neither be created nor destroyed" and "the total energy in a system must remain constant."1 There is very little fluctuation in body mass if energy input (calories in food) equals energy output (calories expended). When energy input exceeds energy output, the excess energy is stored as fat in adipose tissue. The energy balance equation can be unbalanced in only three ways to cause body fat loss:
-Reduce calorie intake below the daily energy requirements.
-Maintain normal caloric intake and increase energy expenditure.
-Combine both methods by decreasing calorie intake and increasing daily energy
expenditure.
Consuming a diet high in fat and protein and low in carbohydrate does not accelerate weight loss. In fact, fat is stored more efficiently in the body than carbohydrate when consumed in excess of calorie requirements. Only about 3% of the calories in ingested lipid are required to convert excess calories to stored body fat, whereas 25% of the calories in carbohydrate "burns" in the conversion process. It is easier for the body to synthesize fat from lipid than from an equivalent amount of carbohydrate when excess calories are consumed 3.
Many populations, such as Asian and African, remain lean on diets extremely high in carbohydrate and very low in fat. A high carbohydrate diet should not be associated with obesity. Epidemiological studies have been done to compare the U.S. diet with other countries' diets. In three studies, it was concluded that obesity was more prevalent in the U.S. even though the other countries had significantly higher carbohydrate intake. In fact, in two of the studies, subjects from other countries had higher total calorie intake. This suggests that dietary fat may play a more important role in obesity than total energy or carbohydrate intake 7.
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