In 2003, Italian researchers looked at the effect of lifestyle changes on a variety of metabolic parameters. 120 obese but otherwise healthy women participated in the study. Half were simply given information about how to make healthy choices, and the other half received counseling on how to lose weight with exercise and a Mediterranean-style diet. After 2 years, the women in the Mediterranean diet group were eating healthy and getting more fiber, complex carbohydrates, and good fats, and less saturated fat and cholesterol than the other group. Both groups also showed drops in body weight, BMI, and blood pressure, though the effect was more pronounced in those following the Mediterranean diet.
Another 2-year study compared the outcomes of 3 restricted-calorie diets: low-fat, low-carb, and Mediterranean. The researchers found that the Mediterranean and low-carb diets resulted in greater weight loss than the low-fat diet, and also provided other beneficial metabolic effects. The authors concluded by saying that both diets appear to be safe, effective alternatives to a low-fat diet.
A review paper published in 2010 analyzed and compared the results of multiple studies regarding the Mediterranean diet and body weight. The analysis drew on a range of trials from both English and non-English publications. The diet was found to have significant effects on weight and body mass index, and appeared to be especially effective when accompanied by physical activity and energy restrictions such as calorie counting, and when followed for 6 months or more. Another study published in 2010 reported that a Mediterranean diet can also reduce one's chance of developing diabetes.