Assessment of serum FGF21 levels, nutritional status and some anthropometric measurements of adult males during fasting

The aim of this study was to determine the effects of hunger on serum Fibroblast Growth Factor 21 (FGF21) levels, nutritional status and anthropometric measurements of adult males during fasting. FGF21 is a significant protein in the process of adaption to fasting due to its effects on liver, adipose tissue, and brain. A total of 12 healthy individuals with normal body mass index, between the ages of 18 to 35 participated to the study. A questionnaire was administered in order to determine individuals' general characteristics, nutrition habits, and smoking and alcohol habits. Anthropometric measurements, 24 hours dietary recall and physical activities were recorded and blood samples were taken four times in following periods; before Ramadan, first week of Ramadan, third week of Ramadan and two weeks after Ramadan. Mean body weight, body mass index, and body fat percentages were significantly decreased in the 1st week of Ramadan (p<0,05). While serum FGF21 levels in 1st week of Ramadan (531,3±377,87pg/ml) showed a decrease compared to before Ramadan (297,5±229,45pg/ml) (p=0,014), serum FGF21 levels after Ramadan (135,9±111,84pg/ml) showed a decrease compared to 3rd week of Ramadan (347,5±289,17pg/ml) (p=0,007). Intake of energy, protein, carbohydrate, fiber, vitamin B1, folic acid, potassium, magnesium, phosphorus, iron and zinc were decreased in the 1st week of Ramadan compared to before Ramadan levels (p<0,05). There were positive correlations between serum FGF21 levels during Ramadan and fat free mass, total body water, protein intake, vitamin B2 intake and phosphorus intake (p<0,05). FGF21 serum levels may show an increase during fasting, however in long term fasting periods like Ramadan it may decrease back to the beginning levels therefore, FGF21 serum levels must be evaluated carefully.