A Mediterranean diet which includes healthy fats is not likely to cause weight gain, according to a study published in The Lancet Diabetes & Endocrinology.
The 5-year randomized control trial included more than 7,400 people between the ages of 55 and 80 who had Type 2 diabetes or a high level of risk or heart disease; more than 90% were overweight or obese. Subjects ate one of three eating plans during a five year period: an unrestricted-calorie Mediterranean diet rich in olive oil, an unrestricted-calorie Mediterranean diet rich in nuts or a control diet with advice to reduce dietary fat.
Weight loss was greatest in the olive oil group (2 pounds versus 1.3 pounds and 0.9 pounds in the low-fat and nut groups, respectively). All groups experienced a slight increase in waist circumference, but this was lower in the Mediterranean diets (0.37 cm nuts, 0.85 cm olive oil, 1.2 cm low-fat).
Research published in Diabetes suggests that the type of fatty acid consumed may affect the body’s tendency to store fat or build muscle.
For seven weeks, 39 young, healthy, normal-weight men and women ate an extra 750 calories daily from a muffin made primarily with either sunflower oil (polyunsaturated fat) or palm oil (saturated fat). Before and after measurements of adipose and lean tissue were taken. While both muffin groups gained a similar amount of weight, the saturated fat muffin group experienced an increase in both liver and visceral fat compared to the polyunsaturated fat muffin group, as well as activity in genes that regulate metabolism, insulin resistance, body composition and fat cell differentiation. The polyunsaturated fat muffin group also saw a three-fold increase in muscle mass compared to the saturated fat group.
Although study authors say more research is needed, they indicate these results could be important for those with metabolic diseases such as diabetes, as well as the elderly for whom maintaining muscle mass is especially important.
Results from a study published in 2015 (Nutrition Journal) show consuming tree nuts was associated with better measures of body composition as well as reduced risk of cardiovascular disease and metabolic syndrome. Researchers used NHANES 2005–2010 data to examine the relationship between tree nut consumption and health risks in 14,386 adults. Tree nuts included almonds, Brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts. Results showed consuming at least ¼ ounce of tree nuts per day was associated with lower Body mass index (BMI), waist circumference, systolic blood pressure, insulin resistance and higher HDL cholesterol, compared with less than ¼ ounce daily.
A systematic review published in The American Journal of Medicine found a Mediterranean-style diet resulted in greater weight loss after one year compared to a low-fat diet.
Authors reviewed five randomized controlled trials totaling 998 subjects who followed a Mediterranean diet, low-fat diet, low-carbohydrate diet or American Diabetes Association (ADA) diet. After at least one year, the Mediterranean diet resulted in greater weight loss compared to the low-fat diet and produced similar weight loss and cardiovascular risk factor level reductions when compared to the low-carbohydrate and ADA diets.