Mediterranean diet could deter overeating, particularly when compared to a Western diet

23 Apr 2019 --- The Mediterranean diet – rich in plant-based proteins, whole fruits, vegetables, legumes, nuts and olive oil – has long been revered for its health-boosting potential. New research has now found that it may also prevent overeating. Scientists at Wake Forest School of Medicine, US, found that nonhuman primates on a Mediterranean diet chose not to eat all the food available to them and maintained a normal weight. In comparison, animals on a Western diet – rich in processed foods – ate far more than they needed and gained weight. The findings provide the first experimental evidence that a Mediterranean diet can protect against increases in consumption, obesity and prediabetes compared to a Western diet.

This is the first preclinical trial to measure the effects of long-term consumption of a Western versus Mediterranean diet on obesity-related diseases under controlled experimental conditions, notes Dr. Carol A. Shively, Professor of Pathology at Wake Forest School of Medicine. Previous research on the effects of diet type on caloric intake were largely based on human population studies that relied on self-reported food intake, which is often unreliable, or rodent studies with nonhuman-type diets.

The study was a 38-month – equivalent to about nine years for humans – prevention trial. The diets were formulated to closely reflect human diets with protein and fat derived largely from animal sources in the Western diet and primarily from plant sources in the Mediterranean diet. However, the two diets contained comparable proportions of fat, protein and carbohydrates.

There were 38 middle-aged females in the study which were randomized to either the Mediterranean or Western diet. Both groups were matched on their baseline weight and body fat and were allowed to eat as much as they wanted throughout the study.

“What we found was that the group on the Mediterranean diet actually ate fewer calories, had lower body weight and had less body fat than those on the Western diet,” says Dr. Shively.

The Mediterranean diet also protected against non-alcoholic fatty liver disease (NAFLD). Obesity is a major cause of NAFLD, and by 2030, one-third of adults in the US are expected to have the disease, and it is the fastest growing reason for liver transplants in young adults.

“The protection against fatty liver disease was perhaps the most novel and important finding. Less hepatosteatosis has not be reported in association with Mediterranean diet consumption, prior to this report. The prevalence of this disease, that obesity and type 2 diabetes cause it, and that it may ultimately lead to liver transplant or death is not well appreciated by Americans. It is a wonderful finding that changing to the delicious Mediterranean diet pattern reduces the risk of this terrible disease,” Dr. Shivley tells NutritionInsight.

“The Western diet was developed and promoted by companies who want us to eat their food, so they make it hyper-palatable, meaning it hits all our buttons so we over-consume. Eating a Mediterranean diet should allow people to enjoy their food and not overeat, which is such a problem in this country,” she explains.

The researchers hope that their findings will encourage people to eat healthier foods that are also enjoyable and can improve human health.

“We are fighting an obesity epidemic. One new diet plan after another claims to result in significant weight loss. But many diet plans are difficult to adhere to, and dieters go off their diets and gain their weight back. In contrast, people really enjoy the Mediterranean diet. It is rich in delicious foods. Instead of going on a diet, people can adopt the Mediterranean diet as a lifestyle, and enjoy it,“ Dr. Shivley explains.

The Mediterranean diet was ranked “best overall” diet by US News and World Report, among nearly 40 it reviewed, sharing the top spot on the list with the National Institutes of Health-developed DASH diet. It has also been found to help prevent aggressive prostate cancer and frailty in the elderly, as well as increase health outcomes for those at risk of cardiovascular disease.