"Eat everything in moderation" may be bad advice according to research produced by The University of Texas Health Science Center at Houston and the Friedman School of Nutrition Science and Policy at Tufts University. In fact, adhering to the old saying may result in a larger waist line, the development of diabetes and poor metabolic health.

Published Oct. 30 in the journal PLOS ONE, dietary diversity was measured by examining the number of different foods consumed in a week, the distribution of calories across different foods and food attributes, such as fiber, trans-fat content and sodium. The new research confirms the modern diet, which includes moderately consuming a variety of high- and low-calorie foods, is actually worse than eating fewer healthy foods. Diet diversity is frequently linked to diminished metabolic health and lower diet quality. 

The U.S. Latino population should be mindful about food quality and diet diversity, particularly because they're already predisposed to high risk for developing type 2 diabetes and related cardiometabolic abnormalities. Also, work-related stress, which Latinos abundantly experience, can increase the risk for type 2 diabetes.

"'Eat everything in moderation' has been a long-standing dietary recommendation, but without much empiric supporting evidence in populations. We wanted to characterize new metrics of diet diversity and evaluate their association with metabolic health," said Marcia C. de Oliveira Otto, Ph.D., first author and assistant professor in the Department of Epidemiology, Human Genetics and Environmental Sciences at UT Health School of Public Health, according to a press release.

The team of researchers analyzed nearly 7,000 Chinese-Americans, whites, blacks and Hispanic-Americans in the United States learn more about the metabolic impact of diet diversity. The researchers looked at the different foods consumed throughout the week, documenting fluctuations in calorie consumption and the impact of food quality on metabolic health. By measuring those factors against gains or losses in waist circumference after five years and the presence of Type 2 diabetes after a decade, researchers were able to gain a broader understanding of the effects of dissimilar diets.

Evaluating variations in food consumption, incidences of diabetes and waist circumference brought researchers to the conclusion that diversity in diet isn't necessarily correlated with better health outcomes. In fact, participants with the highest food dissimilarities experienced 120 percent greater increases in waist circumference when compared to the lowest levels of food dissimilarity. Consistent diets tend to be higher quality, and diets that are dissimilar tend to include the intake of more sweets and processed meats and fewer fruits and vegetables. This explains why food dissimilarity is linked to an expanding waist.

Diet diversity and diet quality are found to be unrelated, and diet quality is related to improved metabolic health. Those with lower diet dissimilarities, thus superior diet quality, were less likely to see a shift waist circumference after five years. Additionally, after 10 years, higher diet quality resulted in a 25 percent lower risk of developing type 2 diabetes. The research determined the healthiest diets include regularly consuming a small range of healthy foods.