In contrast, other primates that received a Western diet ate more food than they needed to. These overeaters became overweight.
The discovery was made by researchers from Wake Forest University in North Carolina. They conducted the first pre-clinical trial that evaluated the consequences of following either a Mediterranean diet or a Western diet for a long period of time. They also examined the effects of both diets on factors associated with obesity.
The results of earlier studies are considered unreliable. Those that included humans depended on self-reports by participants, while studies involving rodents used non-human diets to approximate the effects of a human diet.
The Wake Forest researchers ran a primary prevention trial with non-human primates for 38 months. They designed the test diets to closely resemble the Mediterranean and Western diets.
Both diets had similar ratios of carbohydrates, fats, and protein. The nutritional components of the Western diet equivalent mostly came from animal sources. Meanwhile, edible plants served as the source of fat and protein in the Mediterranean diet. (Related: 11 Gut-healthy foods to add to your diet.)
The researchers matched the groups based on their body fat and weight. They permitted the primates to consume as much food as they desired.
“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,” said Wake Forest researcher Carol A. Shively.
The results, which were published in the journal Obesity, serve as the first empirical evidence of the Mediterranean diet preventing any increases in consumption, obesity risk, and pre-diabetes risk. Meanwhile, the Western diet did the opposite.
The Mediterranean diet also prevented the onset of non-alcoholic fatty liver disease (NAFLD). This medical condition can lead to cirrhosis of the liver and liver cancer.
Conventional treatment for NAFLD requires a risky liver transplant. To make matters worse, NAFLD is quickly becoming one of the most common reasons why young adults undergo liver transplantation.
Obesity is one of the leading causes of NAFLD. Public health experts warn that many adults will develop this liver disease by 2030 if the rise in obesity cases is not addressed promptly.
“Diet composition is a critically important contributor to the U.S. public health, and unfortunately those at the greatest risk for obesity and related costly chronic diseases also have the poorest quality diets,” Shively said. “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 overconsume.”
She added that the Mediterranean diet makes it possible for people to savor their meal without getting tempted to overeat. This can improve the health of consumers while also allowing them to enjoy their food.
It is easy for health-conscious people to try out the Mediterranean diet. Whereas most diets restrict food groups, it encourages the consumption of whole foods.
The Mediterranean diet promotes the consumption of fruits, legumes, nuts, olive oil, vegetables, and whole grains. It also involves eating a lot of fish, which contain healthy omega-3 fatty acids.
Meanwhile, the diet promotes the avoidance of processed foods, red meat, and sugar-rich products.
The Mediterranean diet also encourages people to socialize and spend time with friends.