Monday, January 21, 2008

Diets Rich In Monounsaturated Fats Help Reduce Fat In Midsection

A small study that appeared in the July, 2007 issue of Diabetes Care found that a diet high in monounsaturated fat (MUFA), especially olive oil, redistributed body fat away from the stomach area (depositing it in the leg area), when compared to a diet low in fat and high in carbohydrates. The latter high-carb diet redistributed fat away from peripheral (leg) areas towards central body areas.

The high-MUFA diet also improved insulin sensitivity. It was associated with increased levels of the hormone adiponectin. (Adiponectin is produced by fat cells but is found in lesser amounts in overweight and obese individuals. Lower levels of circulating adiponectin are associated with an increased risk for type 2 diabetes.)

In this study, 11 overweight, insulin resistant volunteers underwent three dietary periods of 28 days each in a crossover design (every volunteer underwent every diet). The diets were either high in carbohydrates, high in monounsaturated fat (MUFA), or high in saturated fat (SAT). Below is the macronutritient composition of the diets. All three diets supplied the same number of calories.

Click for larger.

Their Conclusion:
"Our results indicate that the macronutrient composition of diets may influence body fat distribution and carbohydrate metabolism without affecting total body weight. After a low-fat carbohydrate-rich diet, insulin-resistant patients presented a redistribution of their body fat from peripheral adipose tissue to central body depots. Conversely, a MUFA-rich diet improved insulin sensitivity, and this was associated with increased postprandial adiponectin mRNA gene expression."
So, changing the carbohydrate and fat make-up of the diet, while keeping calorie amounts the same, did not result in weight changes. But it did result in weight redistribution.

Note: Since this study did not differentiate between types of carbohydrates, it could not inform on the effect of choosing carbohydrates that have a lower glycemic index, and that are higher in fiber and resistant starch.

For the study:
Monounsaturated Fat–Rich Diet Prevents Central Body Fat Distribution and Decreases Postprandial Adiponectin Expression Induced by a Carbohydrate-Rich Diet in Insulin-Resistant Subjects