Trial Finds Regional Diet Improves Quality, Sustains Weight Loss

At primary care practices in central North Carolina, 360 adults with a body mass index of 30 or higher entered a two-year weight-loss trial. The question was practical: could a Mediterranean-style diet be reshaped around the foods people in the Southeast already eat, rather than asking them to follow a distant template? The Med-South program was compared with a control program focused mainly on cutting calories.

The researchers, led by Thomas Keyserling and Carmen Samuel-Hodge at the University of North Carolina at Chapel Hill, divided the intervention into three phases: improve diet quality, lose weight while keeping the eating pattern, then maintain the loss. Among participants who returned for follow-up, people in both groups lost and maintained an average of about 4.5 kilograms, or 10 pounds, over 24 months.

The adapted diet did not produce significantly greater weight loss or larger blood-pressure reductions than the calorie-focused program. Its advantage appeared in diet quality. Participants reported more high-quality fats, including monounsaturated and polyunsaturated fats, less carbohydrate intake and higher scores on overall diet-quality indexes. Fruit and vegetable measures improved in both groups; researchers used food questionnaires and the Veggie Meter, which measures carotenoid levels in the skin.

So what changes in practice? A weight-loss program can aim at what people eat, not only how much they eat. For people in the Southeast—where the researchers note higher rates of diabetes, cardiovascular disease and stroke—the Med-South pattern offers a regionally adapted route to nuts, vegetable oils, whole grains, nonstarchy vegetables and fruit, while delivering similar weight loss to calorie restriction and stronger diet-quality results.

The study does not show that the adapted pattern causes more weight loss, and the chronic-disease benefit is a prevention rationale rather than an outcome measured here. The results come from a 24-month randomized clinical trial, published in JAMA Network Open; the researchers say the dietary pattern should be incorporated into lifestyle weight-loss programs because its potential health benefits extend beyond the number on the scale.