Scientists at National Institutes of Health intensely analysed 19 obese people on controlled diets (low fat and low carbohydrate) by inspecting every morsel of food, minute of exercise and breath taken. People were initially given 2,700 calories a day. Then, in a fortnight they tried diets that cut their calorie intake by a third, either by reducing carbohydrates or fat. The team analysed the amount of oxygen and carbon dioxide and also the amount of nitrogen in participants’ urine to calculate the chemical processes taking place inside the body.
The results published in Cell Metabolism showed that after six days on each diet, those reducing fat intake lost an average 463g of body fat. It is 80% more than those cutting down on carbohydrates, whose average loss was 245g.
Both diets led to a fat loss, but people lost more when they reduced fat intake.
However, researchers say that all diets work if the person is sticking to a diet for a prolonged period.
Dr Hall said there was no “metabolic” reason to chose a low-carb diet. He is now analysing brain scans of the participants to see how the diets affect and how rewarding food is.