The effect of increased lipid intake on hormonal responses during aerobic exercise in endurance-trained men

Abstract

In view of the growing health problem associated with obesity, clarification of the regulation of energy homeostasis is important. Peripheral signals, such as ghrelin and leptin, have been shown to influence energy homeostasis. Nutrients and physical exercise, in turn, influence hormone levels. Data on the hormonal response to physical exercise (standardized negative energy balance) after high-fat (HF) or low-fat (LF) diet with identical carbohydrate intake are currently not available. The aim of the study was to investigate whether a short-term dietary intervention with HF and LF affects ghrelin and leptin levels and their modulators, GH, insulin and cortisol, before and during aerobic exercise. Eleven healthy, endurance-trained male athletes (W max 365^29 W) were investigated twice in a randomized crossover design following two types of diet: 1. LF -0.5 g fat/kg body weight (BW) per day for 2.5 days; 2. HF -0.5 g fat/kg BW per day for 1 day followed by 3.5 g fat/kg BW per day for 1.5 days. After a standardized carbohydrate snack in the morning, metabolites and hormones (GH, ghrelin, leptin, insulin and cortisol) were measured before and at regular intervals throughout a 3-h aerobic exercise test on a cycloergometer at 50% of W max . Diet did not significantly affect GH and cortisol concentrations during exercise but resulted in a significant increase in ghrelin and decrease in leptin concentrations after LF compared with HF diet (area under the curve (AUC) ghrelin LF vs HF: P , 0.03; AUC leptin LF vs HF: P , 0.02, Wilcoxon rank test). These data suggest that acute negative energy balance induced by exercise elicits a hormonal response with opposite changes of ghrelin and leptin. In addition, the hormonal response is modulated by the preceding intake of fat.

Exercise-induced GH secretion in the assessment of GH deficiency in adult individuals

“…Since the duration and intensity of exercise strongly affect GH secretion (8,9), this is likely to have influenced diagnostic values. Interestingly, peak GH levels found in control individuals in this study were comparable to earlier studies with similar exercise intensity (7,10). Of note, a linear dose-relationship between exercise intensity and GH secretory response has been suggested in young healthy men (9).…”

“…Of note, a linear dose-relationship between exercise intensity and GH secretory response has been suggested in young healthy men (9). Previous reports indicate that an aerobic exercise duration of at least 20-30 min is required to provoke a relevant GH secretion, whereas a shorter exercise duration may result in comparably high or even higher GH levels if exercise is performed above the aerobic threshold (7,8,10,17). This implies that a certain intensity of exercise may be required over time to optimise diagnostic accuracy (e.g.…”

Significant lowering of plasma ghrelin but not des-acyl ghrelin in response to acute exercise in men

“…While long-term exercise resulting weight loss increases plasma ghrelin level [15,16], short-term running, cycling, or rowing exercise does not alter plasma total ghrelin [17][18][19][20][21][22][23] . A few papers, however, reported that plasma total ghrelin level decreased [24][25][26] or increased [27][28][29] during short-term exercise. Schmidt et al [22] reported that there were no correlations between total ghrelin levels and either of treadmill exercise at 50%, 70%, or 90% maximum oxygen consumption (V ・ O 2max ).…”

Influence of resistance and aerobic exercise on hunger, circulating levels of acylated ghrelin, and peptide YY in healthy males

“…The majority of studies have focused on aerobic (cardiovascular) exercise (31), with only three studies examining the effects of resistance (muscle strengthening) exercise, and these have reported contradictory effects (21,33,47). Resistance exercise is a key component of exercise recommendations for weight control (2) and public health (23, 42); thus, it is important to clarify the effects of resistance exercise on hunger and gut hormones.The effect of acute exercise bouts on total plasma ghrelin concentrations is controversial, with studies reporting no changes either during or postexercise (10,15,26,27,32,39,43,45,47), as well as increases (14,17,25,44) and decreases (21,33,48,50). Acylation of ghrelin is thought to be essential for appetite regulation because only the acylated form of the hormone can cross the blood-brain barrier (41).…”

“…The effect of acute exercise bouts on total plasma ghrelin concentrations is controversial, with studies reporting no changes either during or postexercise (10,15,26,27,32,39,43,45,47), as well as increases (14,17,25,44) and decreases (21,33,48,50). Acylation of ghrelin is thought to be essential for appetite regulation because only the acylated form of the hormone can cross the blood-brain barrier (41).…”