Influence of nutrients on cardiac autonomic function in nondiabetic overweight subjects

The current study sought to determine whether there is a link between cardiac autonomic dysfunction and food intake in overweight subjects. One hundred five nondiabetic overweight (body mass index >27 kg/m2) subjects were studied. Heart rate variations were analyzed during 3 bedside standard tests investigating mainly vagal control: deep breathing, lying-to-standing, and Valsalva tests. The resting metabolic rate and substrate oxidation rates were measured by indirect calorimetry. Dietary intake was estimated from a 3-day recall of food intake. Cardiac parasympathetic dysfunction (PSD) was found in 39 subjects. The sex ratio, age, anthropometric parameters, biochemical parameters and insulin resistance index, resting metabolic rate, and substrate oxidation rates did not differ in the subjects with or without PSD. The total 24-hour energy intake was similar, but the carbohydrate intake was significantly higher in the subjects with PSD (P = .006), and the fat and protein intakes were significantly lower (P = .026 and .045, respectively). In the logistic regression analyses, PSD correlated with carbohydrate and fat intake, independently of serum insulin levels. Glucose oxidation rate correlated negatively with fasting and postglucose serum insulin levels only in the subjects with PSD (P = .006 and .005, respectively). Cardiac parasympathetic dysfunction is associated with higher carbohydrate intake and lower fat and protein intakes in overweight subjects. A sympathetic override may contribute to reducing the glucose oxidation rate in subjects with PSD.