Recent research indicates that focusing on diet quality, such as the Mediterranean-style diet, may enhance overall health more effectively than merely counting calories. A two-year study published in JAMA Network Open found that both a Mediterranean-style diet adapted for the Southern U.S. and a calorie-focused weight-loss program resulted in similar weight loss outcomes.
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The trial involved 360 participants from North Carolina, all with a BMI of 30 or higher, and an average age of 55. Many also had chronic conditions like diabetes and hypertension. Participants were randomly assigned to either the Mediterranean diet (Med-South) group or a control weight-loss program, with 182 in the Med-South group and 178 in the control. The study lasted for 24 months and included assessments at 4, 12, and 24 months.
The Mediterranean diet intervention was structured in three phases: the first phase emphasized improving diet quality, the second phase focused on weight loss, and the third phase targeted weight maintenance. The control group had access to the WeightWatchers program, focusing on calorie reduction while also promoting fruit and vegetable intake.
At the end of the study, both the Mediterranean diet group and the control group achieved similar average weight losses of 3.4% and 3.5%, respectively. However, the Med-South group demonstrated significant improvements in diet quality, including increased consumption of healthy fats, whole grains, fruits, and vegetables, while reducing processed foods and refined carbs. Participants in the Mediterranean group reported a 95% recommendation rate for the program compared to just 68% from the control group.
Christopher Gardner, a professor at Stanford Prevention Research Center, stated that the quality of diets was a secondary focus of the study, which primarily assessed weight loss. Nonetheless, a separate 2024 trial, DIETFITS, found that high adherence to a high-quality diet resulted in the most significant weight loss, highlighting the role of both quality and adherence in effective weight management.
Dietitian Kristin Kirkpatrick emphasized the importance of quality over quantity, noting that while weight loss can occur on a lower-calorie diet, it might not be sustainable long-term. She noted that a higher quality diet can lead to better health outcomes beyond just weight loss, including improved blood sugar regulation and cardiovascular health.
Despite the benefits of higher-quality foods, experts agree that maintaining a calorie balance remains essential for weight loss. Gardner remarked that it is still possible to lose weight on a poor diet if total caloric intake is managed, but choosing higher quality foods supports overall health in the long run.