“‘Eat everything in moderation’ has been a long-standing dietary recommendation, but without much empiric supporting evidence in populations,Â” said study first author Marcia C de Oliveira Otto, assistant professor at The University of Texas Health Science Centre at Houston, US.
Using data from 6,814 participants, the authors measured diet diversity through different measures.
These included the total count (number of different foods eaten in a week), evenness (the distribution of calories across different foods consumed), and dissimilarity (the differences in food attributes relevant to metabolic health, such as fiber, sodium or trans-fat content).
Researchers evaluated how diet diversity was associated with change in waist circumference five years after the beginning of the study and with onset of Type 2 diabetes 10 years later.
Waist circumference is an important indicator of central fat and metabolic health.
The researchers found that more diversity in the diet was not linked to better outcomes.
Participants who had the greatest food dissimilarity actually experienced more central weight gain, with a 120 percent greater increase in waist circumference than participants with the lowest food dissimilarity.
“An unexpected finding was that participants with greater diversity in their diets, as measured by dissimilarity, actually had worse diet quality. They were eating less healthy foods, such as fruits and vegetables, and more unhealthy foods, such as processed meats, desserts and soda,” Otto said.
“This may help explain the relationship between greater food dissimilarity and increased waist circumference,” Otto explained.
The study was published in the journal PLOS ONE.