Growth Hormone, Insulin Resistance Index, Lipid Profile, and Cardiorespiratory Function in Obese and Lean Inactive Young Men: Correlations with Plasma Acylated Ghrelin Levels

Introduction: Plasma ghrelin is influenced by nutritional status and is thought to play a role in acute and chronic regulating of food intake and body weight. The purpose of this study was to compare GH, insulin resistance index, lipid profile, and cardiorespiratory function in obese and lean inactive young men and determine their relationships with plasma acylated ghrelin levels. Methods: Study design of this research was causal-comparative. Obese (n=19, BMI: 31.0 kg/m2) and lean (n=19, BMI: 18.5 kg/m2) young men, without experience of regular physical activity during the previous six months, were selected. After 12 h fasting (at 8 a.m.), blood samples were collected to determine blood parameter levels. Also, maximal oxygen uptake (as indicator of cardiorespiratory function) of subjects was assessed. Results: Insulin levels and HOMA-IR (insulin resistance index) were higher, and GH, acylated ghrelin and maximal oxygen uptake levels were lower in obese men compared to lean men (P<0.01). No significant differences were observed in systolic and diastolic blood pressure, fasting blood glucose, and lipid profiles between obese and lean groups (P>0.01). Plasma acylated ghrelin concentrations were negatively correlated to body mass, body fat percent, body mass index, insulin and HOMA-IR, and positively correlated to GH levels and maximal oxygen uptake (P<0.01). No significant correlations were observed between plasma acylated ghrelin concentrations and systolic and diastolic blood pressure, fasting blood glucose, and lipid profiles in none of groups (P>0.01).Conclusion: Obese and lean inactive young men had different levels of acylated ghrelin, GH, insulin, insulin resistance index, cardiorespiratory function and body fat percent. Body fat percent, insulin, and GH levels appear to be the strongest determinant factors of acylated ghrelin levels.