Two studies released this week may have weight loss hopefuls scratching their heads, each providing seemingly conflicting information.
On September 2, the Annals of Internal Medicine published a study that showed higher rates of weight loss for adherents to a low-carb diet, compared to low-fat diet. Then, on September 3, a study published in the Journal of the American Medical Association found that those that followed either a low-carb or low-fat diet had, on average, equal weight loss.
In the first study, researchers conducted a randomized, controlled trial at Tulane University Health Sciences Center. One hundred sixty-eight people were randomly assigned either low-carb or low-fat diets. After 12 months, the low-carb dieters lost an average of 12 pounds, while the low-fat camp only lost four pounds. The low-carb group also showed better gains in HDL cholesterol levels (“good” fat) as well as a lowering of cardiovascular risk factors.
In the study published in the Journal of the American Medical Association, researchers evaluated results of 48 trials of branded diets—from the low-carb Atkins and South Beach to low-fat options like the Ornish diet. Also included were other options like Jenny Craig and Weight Watchers. The results showed that dieters, regardless of approach, lost the same 16 average pounds per year.
So who’s the winner here?
According to Howard LeWine, M.D. of Harvard Health Publications, any balanced diet can lead to a successful weight loss regimen and overall healthy lifestyle. Writing on the Harvard Health Blog, LeWine explained that many factors go into whether or not a diet will be successful for a person. Factors such as genes and environment determine metabolism and body fat percentages, while exercise and making healthy food choices always makes a difference when it comes to results.
“One eating strategy that can provide all that is the so-called Mediterranean diet,” he writes. “Many studies have linked following this type of diet to longer life and less heart disease, diabetes, cancer, and other chronic conditions.”
He recommends four or more servings of both fruit or vegetables per day, at least 4 tablespoons of olive oil, a handful of nuts a few times per week, whole grains, three or more servings of fish per week and one serving or yogurt or cheese per day.
In discussing the results with the Boston Globe, Dariush Mozaffarian, M.D., cardiologist and dean of the Friedman School of Nutrition Science and Policy at Tufts University, explained that the results of are not in fact contradictory.
“In the single trial published in the Annals journal, researchers didn’t ask people to reduce their calorie intake but just instructed them to change the composition of their diet — eating fewer carbohydrates or less fat,” he said. “In the JAMA meta-analysis looking at commercial diet plans, participants reduced how much they ate and also altered their diet composition, so it’s impossible to know what actually led to the weight loss.”
Mirroring the sentiments of LeWine, Mozaffarian explained that making healthy choices is far more important in determining overall health and diet success.
“I think a traditional Mediterranean diet based on yogurt, cheese, dairy products, legumes, and fish is the way to go,” he said.