Effect of Ramadan fasting on some indices of insulin resistance and components of the metabolic syndrome in healthy male adults

The purpose of the present study was to evaluate the effect of Ramadan fasting on insulin sensitivity in subjects with the metabolic syndrome. Males (n 55; age 34.1 (SD 8.9) years) with the metabolic syndrome were studied. Blood pressure, waist circumference, body weight, HDL-cholesterol (HDL-C), TAG, fasting plasma glucose (FPG), fasting blood insulin and insulin resistance indices (quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment of insulin resistance (HOMA-IR) and reciprocal index of HOMA-IR (1/HOMA-IR)) were evaluated before and after 30 d of Ramadan fasting (two meals at 12 h intervals). The dietary intake was estimated by 24 h recall before and after fasting. The total daily energy intake was decreased by 234.6 (SD 88.2) kJ/d in the fasting period (P = 0.005). 1/HOMA-IR, QUICKI and HDL-C were significantly increased (P = 0.005, P = 0.001 and P = 0.004) and FPG significantly decreased (P < 0.005) after fasting. Simple linear regression analysis demonstrated that HOMA-IR, 1/HOMA-IR and QUICKI were related to waist circumference after intervention (r 0.458, P < 0.001; r -0.396, P < 0.05; r -0.342, P < 0.05). In conclusion, the present study showed that the combined change in the number and timing of meals and portioning of the entire intake into only two meals per d may increase insulin sensitivity in subjects with the metabolic syndrome even when the decrease in energy consumption is minimal. © The Authors 2008