Is weight loss really just about calories in, calories out — or does diet quality make a difference?Researchers followed 360 adults with obesity for two years. Half were assigned to a Mediterranean-style program that emphasized healthy fats, whole grains, fruits and vegetables, while limiting refined carbs and processed foods.The other half used WeightWatchers, which focused primarily on cutting calories, while encouraging more fruits and veggies.After two years, both groups lost about 4% of their body weight. But the Mediterranean-style group made significantly greater improvements in diet quality. “My key takeaway was the profound impact of the Mediterranean diet on improving our overall eating habits in a way that's sustainable.” (Emily Case, Registered Dietitian, Northwell Health)Emily Case, a registered dietitian at Northwell Health, wasn’t part of the study but says the Mediterranean diet provides a "clear blueprint for food choices that are healthy and nutritious.""These directly address the underlying causes of chronic disease, diabetes and heart disease by giving you more healthy fats, whole foods and fewer unhealthy carbs, which are key for reducing these things." (Emily Case, Registered Dietitian, Northwell Health)The authors say more research is needed to understand how diet quality affects obesity-related health outcomes.In the meantime, they say these findings suggest weight-loss programs should put greater emphasis on diet quality.Source: JAMA Network OpenAuthor Affiliations: University of North Carolina at Chapel Hill, East Carolina University, Duke University, Morehouse School of Medicine, Simmons University, Boston,, Harvard T.H. Chan School of Public Health, Duke-NUS Medical School.Sign up for our weekly HealthDay newsletter