Metabolic and hormonal effects of an 8 days water only fasting combined with exercise in middle aged men

Abstract

Optimal nutrition and physical activity are vital for enhancing physical performance and preventing metabolic diseases like obesity. Recently, interest has grown in long-term fasting, particularly water-only fasting, which involves no food intake and unlimited water consumption. Our study investigated the effects of 8 days of water-only fasting combined with aerobic exercise in 13 middle-aged men, focusing on metabolic, hormonal, and immune changes. Results showed that fasting had a more significant impact than exercise, leading to changes in glucose, uric acid, IGF-1, IGF-2, GH, leptin, and cortisol, improved total antioxidant status (TAS), and reduced lipid peroxidation. While exercise enhanced the effects of fasting on triglycerides, insulin, GH, TAS, PerOX, and IL-6, changes in total protein and lactate were solely due to exercise. Overall, combining fasting and exercise led to a metabolic shift from carbohydrates to fatty acids and hormonal adaptations to stress. These results, although derived from a small group of patients, offer a promising outlook for further research into the effects of fasting combined with physical activity on health and weight maintenance.

Keywords: Fasting; Hormonal changes; Immunity; Metabolism; Physical activity.