Habitual dietary intake and insulin sensitivity in lean and obese adults

Abstract

Studies in rodents have shown that short-term increases in dietary fat result in fat cell enlargement and insulin resistance. In humans, although high-fat diets have been associated with obesity, little is known about the specific metabolic effects of these diets. In this study we explored possible associations between habitual dietary composition and insulin sensitivity. Twenty-two lean and 23 obese subjects were characterized by dietary history (food frequency questionnaire), anthropometrics, oral glucose tolerance, and insulin sensitivity (S_I, from the minimal model). As shown previously, body mass index was positively correlated with percent of energy intake as fat (r = 0.47, P = 0.001). Increasing fat intake was also associated with diminished S_I (r = −0.41, P = 0.01). In contrast, S_I was positively correlated with fiber intake (r = 0.43, P = 0.007). Multivariate analysis confirmed the importance of dietary fiber for S_I. We conclude that habitually low dietary fiber intake, along with elevated dietary fat, correlates with diminished S_I in otherwise healthy lean and obese subjects.