Sticking to a diet that limits choices, not calories, may help you control weight and prevent Type 2 diabetes. Experimenting with new foods did not help people in a recent study lose weight or whittle their waistlines, according to findings published in PLOS ONE. Researchers say just the opposite occurred. Those who ate the most varied diet experienced more weight gain and saw an increase in waist measurement that was 120 percent greater than those who ate the most restricted diets.
Although ‘eat everything in moderation’ has been a long-standing dietary recommendation, there hasn’t been much evidence to back up the recommendation, according to Marcia C. de Oliveira Otto, Ph.D., who is the study’s lead author. She said researchers wanted to examine the impact of diet diversity on metabolic health.
“An unexpected finding was that participants with greater diversity in their diets, as measured by dissimilarity, actually had worse diet quality,” she said. “They were eating less healthy foods, such as fruits and vegetables, and more unhealthy foods, such as processed meats, desserts and soda,” said Otto.
In the study, people first selected foods like sausage, soft drinks, and candy and then added produce and whole grains to their diet. The benefits of including healthy foods were simply outweighed by the fat, sugar and preservatives in their priority food choices.
“Eating a range of quality foods may be more effective in promoting health than the old advice of ‘eating everything in moderation,'” Otto says.
Choosing less nutritious foods on a varied diet may explain the participants’ expanding waistlines, according to the study’s findings. Waist circumference is important as an indicator of central fat and metabolic health, and researchers evaluated changes in waistlines five years after the beginning of the study. Those eating a higher-quality diet saw about a 25 percent lower risk of developing Type 2 diabetes after 10 years, according to researchers.
“Americans with the healthiest diets actually eat a relatively small range of healthy foods,” said Dariush Mozaffarian, M.D., Dr.P.H. He is the study’s senior author. “These results suggest that in modern diets, eating ‘everything in moderation’ is actually worse than eating a smaller number of healthy foods.”
Researchers asked more than 7,000 people about their eating habits. They examined the number of different foods participants eat in a week and the nutritional similarity of those foods. They also studied the number of calories in each food.
The study was conducted by researchers at The University of Texas Health Science Center at Houston (UTHealth) and the Friedman School of Nutrition Science and Policy at Tufts University.
Otto is an assistant professor in the Department of Epidemiology, Human Genetics and Environmental Sciences at UTHealth School of Public Health. Mozaffarian is dean of the Friedman School of Nutrition Science and Policy at Tufts University in Boston.