Soluble Fiber Intake and Abdominal Obesity

Intra-abdominal fat and liver fat are most closely linked to insulin resistance and type 2 diabetes.  That’s why waist circumference is now considered a better marker of cardiovascular risk than weight or body mass index.  Scientists at Wake Forest, North Carolina, have studied the lifestyle factors responsible for abdominal fat increase in two minority populations, African Americans and Hispanic Americans.  Their findings are published in the journal Obesity. 

Over 1,100 participants aged 18 to 81 were enrolled, and given a physical exam, an extensive questionnaire on lifestyle factors, and a CT (computed tomography) scan.  Physical activity was recorded by self-report and nutritional factors in a semi-quantitative food frequency questionnaire.  Visceral (intra-abdominal) and subcutaneous fat was measured at the level of L4-L5 lumbar vertebrae on the CT.  The same procedure was repeated 5 years later.

After 5 years, the percentage change in fat accumulation was analyzed in relation to smoking, physical activity, average total calorie intake, and poly- and mono-unsaturated and saturated lipids intake, protein intake, and percentage of calories from sweets, soluble and insoluble fiber.

Increased soluble fiber and vigorous physical activity were associated with a reduced increase in visceral fat, which was independent of body mass index (BMI).  For each 1 gram increase in soluble fiber the rate of visceral fat accumulation decreased by 3.7%.  There was no such association between soluble fiber intake and subcutaneous fat; however, moderate physical activity was associated with a 3.6% decrease in subcutaneous fat accumulation.   

So how do you achieve a relevant amount of soluble fiber in your diet?  According to the lead researcher, ten grams of soluble fiber can be achieved by eating two small apples, one cup of green peas or one half-cup of pinto beans.  Or by undertaking ‘moderate activity’, which means exercising vigorously for 30 minutes, 2-4 times a week.  Of course, there may be the temptation to take 3 teaspoons of Metamucil® or Benefiber® a day.