For those facing the daunting prospect of losing weight, calorie counting, coupled with exercise, has long been a steadfast and safe, if uncomfortable, way to do so. But new research indicates that not all calories are created equal.
After weight loss, the lost pounds tend to return. Normally, this may be blamed on a lack of willpower but biology is also a culprit. After dieting, the body’s metabolism slows, causing the body to regain its lost mass. Researchers at the Boston Children’s Hospital set out to find if certain diets are worse offenders at regaining hard-earned weight loss than others.
Scientists studied 21 subjects who were tasked with losing 10 to 15 percent of their body weight. After their weights stabilized, subjects completed three diets in random four week intervals. The first was a low-carbohydrate diet, modeled after the one popularized by Dr. Atkins, in which subjects received 10 percent of their caloric intake from carbohydrates, 30 percent from protein, and 60 percent from fat. The second was a low-glycemic diet, comprised of 40 percent carbohydrates, 40 percent from fat, and 20 percent from protein. Low-glycemic diets are comprised of fruits, vegetables, legumes, minimally processed grains, and healthy fats. The third was a low-fat diet, which emphasizes whole grains, fruits, and vegetables. The low-fat diet was made up of 60 percent carbohydrates, 20 percent fat, and 20 percent from protein.
The study measured the participants by examining stable isotopes to find out their total energy expenditure.
The team found that low-fat diets caused participants’ metabolism to slow the furthest, causing the most weight regain. Though that particular diet is the one favored by the U.S. Government and Heart Association, it also caused an unhealthy lipid pattern and insulin resistance. The low-carbohydrate diet was the best at maintaining participants’ metabolism, but increased cortisol levels and C-reactive protein levels, both of which can raise cardiovascular risk. Increased cortisol levels also led to insulin resistance.
In all, the researchers were most impressed with the low-glycemic diet. Its composition ensured that participants’ blood sugar levels were kept relatively steady, and the scientists believed that it was an easier diet to maintain, since it does not virtually eliminate whole food groups.
The results of the study were published in the Journal of American Medical Association.