Objective: To investigate the effects of a low-fat and high-carbohydrate (LF-HC) diet on the physiological and biochemical indexes in healthy youth with different body mass index (BMI).
Methods: Seven overweight participants [BMI=(27.82 +/- 1.64) kg/m2] and 49 age-matched controls [BMI = (20.06 +/- 2.41) kg/ m2] were given a washout diet for 7 d, followed by a LF-HC diet for 6 d. The washout diet contained 31.1% fat and 54.1% carbohydrate, and the LF-HC diet contained 14.8% fat and 70.1% carbohydrate of total energy. Anthropometric measurements were conducted on the mornings of the first, eighth and fourteenth days. Serum samples were prepared from twelve-hour fasting venous blood. Biochemical indexes including lipids; glucose and insulin were measured with routine methods. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated.
Results: At baseline, the control group had lower levels of body mass (P = 0.000), BMI (P = 0.000), waist-hip ratio (P = 0.000), systolic blood pressure (P = 0.001), diagnostic blood pressure (P = 0.016) and triglycerides (P = 0.006), and a higher level of HDL cholesterol (P = 0.005) than the overweight group. When compared with those before the ILF-HC diet, total cholesterol (P < 0.05) and LDL cholesterol (P < 0.05) decreased, and insulin (P < 0.05) and HOMA-IR (P < 0.05) increased in both the control group and the overweight group after the LF-HC diet. Increased triglycerides (P = 0.000) were observed only in the control subjects, and HDL cholesterol (P = 0.018) increased only in the overweight subjects after the LF-HC diet.
Conclusion: The responses of serum TG and HDL-C to the LF-HC diet are related to BMI in healthy youth.