Research shows the potential of heat treatments to promote healthier aging

New research in mice suggests that daily time in a warm environment like a sauna may help older adults, especially women, fight age-related obesity and insulin resistance. The study shows the potential of heat treatments as a simple way to promote healthier aging.

The researchers found that older female mice given a daily 30-minute total-body heat treatment gained less weight and showed better use of insulin, which helps regulate blood sugar levels. The researchers also identified the biological processes responsible for these beneficial effects.

Compared to men, women are more likely to be obese or overweight. This is especially true after menopause, due to the loss of estrogen in the body. Our study suggests that whole-body heat therapy may serve as an effective, noninvasive solution for managing the weight gain and insulin resistance associated with menopause.”

Soonkyu Chung, PhD, leader of the research team, associate professor in the Department of Nutrition, University of Massachusetts Amherst

Rong Fan, a doctoral candidate advised by Chung, will present the findings at NUTRITION 2024, the flagship annual meeting of the American Society for Nutrition, held June 29 through July 2 in Chicago.

“Heat therapy may be a practical option for people with excess belly fat and a higher risk of metabolic diseases caused by hormonal changes during menopause,” Fan said. “It can easily be incorporated into daily health care through regular sessions in saunas, heated baths or with specialized heat wraps.”

For the study, the ovaries of older female mice were removed to model postmenopausal conditions. To induce weight gain, the mice were fed a Western diet containing 45% of calories from fat. One group of mice received 30 minutes of daily heat therapy in a heating chamber set at 40℃ (104°F) for 12 weeks, while the other group received no heat treatment.

The mice that received the heat treatment showed no tissue damage and showed significantly reduced lactate dehydrogenase levels, indicating less aging-related tissue damage. The therapy also effectively attenuated the weight gain caused by a high-fat diet.

Compared to mice that did not receive the treatment, mice that received heat therapy showed significant improvements in insulin sensitivity and insulin signaling, as well as reduced fat accumulation in key areas like the liver and in brown fat. While fat tissue stores energy, brown fat is a metabolically active type of fat that helps the body burn more energy. Research has shown that people tend to lose brown fat as they age and enter menopause, contributing to a slower metabolism.

The researchers also investigated the molecular mechanisms involved in the beneficial effects of heat therapy. They found that heat triggers several molecular processes that help the body use energy more efficiently and burn fat. One key player is a protein known as TRPV1, which functions as a calcium ion channel in the cell membrane. When TRPV1 is activated by heat, it initiates a process known as the futile calcium cycle, in which the body uses energy (in the form of ATP) to pump calcium ions across cell membranes. This process helps increase the amount of energy the body burns.

TRPV1 activation and the subsequent calcium cycle also stimulate the breakdown and burning of fats. This reduces fat accumulation in tissues such as the liver and helps improve the body’s insulin sensitivity, which is crucial for overall metabolic health. “This chain of events suggests that regular application of heat can mimic the effects of calorie burning and fat loss,” Fan said. “It could be particularly beneficial for people who find physical activity challenging, offering a relaxing way to improve metabolic health.”

The researchers note that more research is needed to determine the optimal duration and intensity of heat exposure for health benefits and to confirm its safety and effectiveness in different populations.

Fan will present this research on Monday, July 1 from 8:08 to 8:12 a.m. CDT during the Nutritional Interventions and Metabolic Insights in Aging and Obesity Poster Theater Flash Session at McCormick Place (abstract; presentation details).