Mechanism of Action of Acupuncture in Obesity: A Perspective From the Hypothalamus

Obesity represents one of the greatest public health challenges of our time, affecting more than two billion adults worldwide. This condition, characterized by excessive accumulation of body fat, does not simply result from a lack of self-control, but rather from a complex imbalance between energy intake and energy expenditure. The consequences of obesity extend far beyond aesthetic concerns, significantly increasing the risk of developing hypertension, diabetes, cardiovascular problems, fatty liver disease, and sleep apnea. In addition to the high costs to health care systems, obesity drastically reduces quality of life.

Conventional treatments, which include dietary restrictions, physical exercise, and, in extreme cases, bariatric surgery, often yield limited results and present difficulties in maintaining weight loss. The medications approved for the treatment of obesity are few and generally cause unpleasant gastrointestinal side effects such as nausea, vomiting, and diarrhea. Given these limitations, there is growing interest in complementary therapies such as acupuncture, an ancient practice of traditional Chinese medicine that has demonstrated efficacy in body weight control.

The objective of this study was to investigate the mechanisms by which acupuncture acts in the treatment of obesity, focusing specifically on the role of the hypothalamus, a brain region fundamental to appetite control and energy balance. The researchers conducted a comprehensive narrative review of the scientific literature, analyzing experimental studies conducted primarily in animal models, particularly rats. The methodology involved analyzing how different acupuncture and electroacupuncture techniques influence hypothalamic nuclei, appetite-related neuropeptides, connections with the brainstem, and peripheral hormonal signals. The authors specifically examined the arcuate nucleus of the hypothalamus, considered the integration center for metabolic signals, as well as other important nuclei such as the paraventricular, ventromedial, dorsomedial, and the lateral hypothalamic area.

The research also investigated how acupuncture affects peripheral hormones such as leptin, insulin, ghrelin, and cholecystokinin.

The results revealed that acupuncture acts through multiple integrated mechanisms in body weight control. In the arcuate nucleus of the hypothalamus, acupuncture demonstrated a significant reduction in the expression of neuropeptides that stimulate appetite, such as NPY (neuropeptide Y) and AgRP (agouti-related protein). Simultaneously, it increases the production of substances that suppress appetite, including POMC (pro-opiomelanocortin) and α-MSH (alpha-melanocyte-stimulating hormone). Electroacupuncture proved particularly effective when applied to specific points such as Zusanli and Sanyinjiao, promoting positive changes in gene expression of these neuropeptides.

In the other hypothalamic nuclei, acupuncture demonstrated an increase in the electrical activity of the ventromedial nucleus, known as the "satiety center," while reducing activity in the lateral hypothalamic area, traditionally called the "hunger center." Regarding peripheral hormones, the studies showed that acupuncture can normalize leptin levels, improve insulin sensitivity, modulate ghrelin levels, and increase cholecystokinin, a gut hormone that promotes satiety.

The clinical implications of these findings are promising for both patients and health care professionals. For patients struggling with obesity, acupuncture emerges as a safe and relatively economical therapeutic alternative, with few side effects compared with conventional medications. The technique acts in a holistic manner, simultaneously addressing multiple systems involved in weight control, from central appetite regulation to peripheral metabolism. For health care professionals, these results provide a solid scientific basis for incorporating acupuncture into obesity treatment protocols.

Understanding the underlying molecular mechanisms allows for a more targeted and effective application of the technique. The findings suggest that specific points such as Zusanli, Zhongwan, and Guanyuan may be especially effective, and that electroacupuncture may offer additional advantages due to the possibility of standardizing stimulation parameters. The research also indicates that treatment should be maintained for adequate periods to allow the necessary neurochemical adaptations.

However, the study presents some important limitations that should be considered when interpreting the results. First, most of the evidence is derived from studies in animal models, particularly rodents, and direct extrapolation to humans must be made with caution. Physiologic differences between species may influence the response to treatment. Second, there is still no complete standardization of acupuncture protocols for obesity, including point selection, stimulation frequency, duration, and intensity of treatment.

This variability between studies may affect the reproducibility of results. Third, the detailed molecular mechanisms are not yet completely elucidated, especially with regard to the complex interactions between the different neural systems involved. Large-scale controlled clinical studies in humans are needed to confirm the efficacy and safety observed in experimental models. Despite these limitations, the research represents a significant advance in the scientific understanding of how acupuncture may be a valuable tool in combating the global obesity epidemic, offering hope for millions of people seeking effective and safe alternatives for body weight control.