How exercise affects appetite in obese men

How exercise affects appetite in obese men

Moderate exercise may help regulate appetite in obese men by influencing key hormones such as IL-6, irisin and NPY, providing potential insights for weight management strategies.

The obesity epidemic, which affects over one billion people worldwide, presents an ongoing public health challenge. Eating habits are considered one of the main factors contributing to the development of obesity.

Appetite is regulated by both environmental and intrinsic factors that act on the brain. A recently published study inPhysiological reportsExamines how appetite-associated factors affect appetite perception in obese men.

Obesity and appetite hormones

Gastrointestinal hormones have been extensively studied for their role in regulating appetite-induced appetite. Recently, the roles of interleukin 6 (IL-6), IL-7, irisin, and leptin from muscle cells, adipose deposits, and inflammatory cells in appetite-regulating pathways have been investigated. For example, leptin release from skeletal muscle has been shown to directly influence energy regulation, with increasing leptin levels being implicated in feelings of satiety.

Neuropeptide Y (NPY) is the major neuropeptide associated with increased appetite in the central nervous system (CNS). However, it remains unclear whether systemic circulation of NPY is involved in appetitive behavior.

The body reacts differently to appetite hormones in obese and slim people. For example, lean people experience satieties after moderate continuous aerobic exercise, which is accompanied by altered gastrointestinal hormone levels. However, these effects of exercise have not been observed in obese individuals.

To date, few studies have examined fluctuations in appetite hormones and other appetite-related factors associated with obesity. However, some evidence suggests that obese and obese individuals experience a loss of appetite after moderate exercise.

About the study

The present study is the first to evaluate the short-term effects of moderate aerobic exercise on hormone and cytokine levels in obese individuals. The study cohort included 11 men with a mean body mass index (BMI) of 35.3 kg/m2 and peak oxygen consumption (VO2peak) of 29 ml/kg/min.

The first mouse experiment involved cycling at 60% of VO2 peak while control participants rested quietly for 60 minutes. Investigators examined how hungry participants felt before breakfast, 30 minutes after breakfast, and at half-hourly intervals after exercise until 1:15 a.m. IL-6, IL-7, irisin, NPY and leptin levels were measured in all study participants.

Study results

In the mouse group, acutely increased IL-6 and irisin levels were observed after training compared to those in the resting group compared to fasting and conditions. These concentrations remained high one hour after exercise.

NPY levels decreased by one hour compared to fasting or conditions. No significant change was observed in IL-7 or leptin levels.

The study participants in the mouse experiment felt less hungry immediately after training and an hour after training.

Comparison with previous studies

The reported increase in IL-6 levels confirms previous findings in obese subjects; However, the IL-6 response appears to vary with the number of muscles used during exercise and exercise duration. With continued exercise, glycogen reserves in muscle tissue are consumed primarily in slow-twitch fibers, stimulating IL-6 release.

IL-6 increased 100-fold after training. Because IL-6 enters the circulation, it can cross the blood-brain barrier to influence appetite after exercise. In previous studies, systemic injection of IL-6 at a dose four times normal significantly reduced food consumption, indicating its potential role in exercise-induced appetite loss.

The 20% increase in irisin levels is similarly consistent with previous reports, with the release of this hormone likely dependent on the duration of physical activity. Specifically, irisin levels are naturally higher in obese individuals due to irisin resistance.

The reduction in NPY levels after training contradicts previous results. NPY is secreted by multiple cell types in the body, increases with greater duration of exercise, and is present at higher concentrations in obese or overweight individuals.

Reduction in appetite after exercise is not consistently reported across studies and may vary with stress, mood, and the individual's perception of the level of exertion. The study results suggest that changes in appetite after exercise may be attributed to increasing levels of IL-6 and irisin, which are accompanied by lower levels of NPY.

Conclusions

Study results reflect a dynamic shift in several myokines and cytokines following moderate continuous exercise in obese men. The effect of these changes may decrease appetite. The target of these hormones therefore has the potential to effectively reduce weight and achieve energy balance in obese men.

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