The battle between low-fat and low-carb diets has been a long one, and is showing no signs of stopping. For years, it seems as though the low-carb diet has been accepted as the better option for short-term weight loss; however, latest report suggests that perhaps the low-fat diet might be better for weight-loss in the long run.
A low-carb diet was thought to be better because it meant the lowering of insulin levels. Insulin regulates fat tissue, so lowering insulin levels was supposed to give people an edge in burning fat.
Kevin Hall, a metabolism researcher at the National Institute of Diabetes and Digestive and Kidney Diseases wanted to test this theory, and hence conducted studies in partnership with the US National Institutes of Health, or the NIH. The report was published in Cell Metabolism, concluding that the low-fat diet may actually be better.
In order to conduct the test, researchers had to create an extremely rigorous study, with research around weight loss being notoriously difficult to do accurately. In the test, 19 overweight people who volunteered to stay at the NIH were recruited. While they were there, everything they ate was recorded and every time they did exercise, it was prescribed by scientists. The team basically wanted to find out how an obese body adapted to the cutting of fat from a diet versus the cutting of carbohydrates.
"Unless we do the kind of study that we have done here, where we basically lock people up for an extended period of time, control everything, and make sure we know exactly what they eat...then we don't have the kind of control that's required to answer these really basic questions," said Hall in an interview with Time.
During two different two-week stays, the volunteers ate the same thing each day. During the first two-week period, individuals ate a balanced, normal diet during the first five days. Then, they were switched to a diet with a 30 percent reduction in calories, half the team doing so with a low-fat diet and the other half with a low-carb diet. During the second two-week period, the same thing was done expected participants switched diets.
As it turns out, those on the low-fat diet lost 463 grams of fat, almost double the 245 grams lost on average during the low-carb diet.
While the team behind the study is confident in its accuracy, they do say that it is small and that in the real world, when people are more active, results may be a little different.