It found that people who cut back on added sugar, refined grains and highly processed foods while concentrating on eating plenty of vegetables and whole foods — without worrying about counting calories or limiting portion sizes — lost significant amounts of weight over the course of a year.
“The strategy worked for people whether they followed diets that were mostly low in fat or mostly low in carbohydrates. . . .. their success did not appear to be influenced by their genetics or their insulin-response to carbohydrates, a finding that casts doubt on the increasingly popular idea that different diets should be recommended to people based on their DNA makeup or on their tolerance for carbs or fat.”
The study compared how overweight and obese people would fare on low-carbohydrate and low-fat diets . . . and tested the hypothesis — suggested by previous studies — that some people are predisposed to do better on one diet over the other depending on their genetics and their ability to metabolize carbs and fat. (A growing number of services have capitalized on this idea by offering people personalized nutrition advice tailored to their genotypes.)
The participants were encouraged to meet the federal guidelines for physical activity but did not generally increase their exercise levels,
The new study stands apart from many previous weight-loss trials because it did not set extremely restrictive carbohydrate, fat or caloric limits on people and emphasized that they focus on eating whole or “real” foods — as much as they needed to avoid feeling hungry.
They did not have to restrict or even think about calories.
“Dr. Walter Willett, chairman of the nutrition department at the Harvard T. H. Chan School of Public Health, said the study did not support a “precision medicine” approach to nutrition, but that future studies would be likely to look at many other genetic factors that could be significant. He said the most important message of the study was that a “high quality diet” produced substantial weight loss and that the percentage of calories from fat or carbs did not matter, which is consistent with other studies, including many that show that eating healthy fats and carbs can help prevent heart disease, diabetes and other diseases.”
*led by Christopher D. Gardner, the director of nutrition studies at the Stanford Prevention Research Center. It was a large and expensive trial, carried out on more than 600 people with $8 million in funding from the National Institutes of Health, the Nutrition Science Initiative and other groups.