Why does intensive exercise reduce appetite?
Have you ever noticed the phenomenon that your appetite is poor within hours after intense workouts? Now a new scientific research reveals the reason underlying this phenomenon.
When engaged in intense exercise, people's body temperature increases. Immediately after exercise, they generally show less interest in food. Why this occurs has not been fully understood. Six researchers from Albert Einstein College of Medicine, including Jae Hoon Jeong, Dong Kun Lee, Shun-Mei Liu, Streamson C. Chua Jr., Gary J. Schwartz, and Young-Hwan Jo, carried out experiments to study the problem. They found that exercise may alter appetite post-workout via a brain region, known as the arcuate nucleus of the hypothalamus (ARC).
Their findings were published in a paper titled "Activation of temperature-sensitive TRPV1-like receptors in ARC POMC neurons reduces food intake," appearing in PLOS Biology on April 24, 2018.
According to corresponding author Dr. Young-Hwan Jo, the hypothalamus participates in regulating metabolism and weight. Dr. Jo and colleagues set out to investigate whether neurons (nerve cells) in this brain region would emit a stop eating signal in response to temperature increases induced by exercise.
They mainly looked at the proopiomelanocortin (POMC) neurons in the ARC. They found that ARC POMC neurons expressed functional TRPV1 channels. TRPV1 receptors
, or called capsaicin receptors, are known to sense heat. Moreover, the researchers discovered that activation of TRPV1 receptors induced the release of a feeding-regulating hormone from ARC POMC neurons and consequently reduced food intake.
Furthermore, they found that exercised mice ate much less food compared with non-exercised mice. Importantly, exercise had no effect on food intake in mice silencing the Trpv1 gene in ARC POMC neurons. These suggest that rise in ARC temperature can activate TRPV1 receptors in ARC POMC neurons, leading to a reduction in food intake.
In conclusion, the study identifies a mechanism by which TRPV1-expressing ARC POMC neurons sense brain temperature increases and reduce food intake. A better understanding of this mechanism would help understand the regulation of energy intake and expenditure in the body.
The study provides an explanation for why people show less interest in food after intensive exercise. The reason lies in the brain.
The study would also have applications in the intervention of overweight and obesity. For example, it may help develop strategies for controlling appetite.