Aging Thermogenic Fat Loses Flexibility, Study Finds, Offering Clues to Metabolic Health

Researchers from City of Hope have identified a biological mechanism explaining why people become more sensitive to cold as they age, according to a study published in Nature. The work, led by associate professor Qiong "Annabel" Wang, shows that thermogenic fat—a specialized tissue that burns calories to produce heat—loses its ability to respond quickly to temperature drops in older mice.

The study reveals that thermogenic fat contains a mix of highly active and less active cells, allowing the body to dial heat production up or down as needed. With age, this system becomes less flexible, so older mice took longer to ramp up heat generation when exposed to cold. The experiments were conducted primarily in mice, though researchers observed a similar cell mixture in human thermogenic fat samples.

By blocking a specific biological pathway with the drug mifepristone, scientists partially restored heat production in older mice. However, mifepristone affects many body systems and is not a candidate for treating age-related cold sensitivity. The findings suggest the decline may be reversible, but any future therapy would need to be precise and safe.

Wang noted that thermogenic fat also burns glucose and fat, and its activity declines with age. Restoring this activity could deepen understanding of metabolic disorders like obesity and type 2 diabetes. The study is early-stage and does not offer clinical recommendations.

What to know: Thermogenic fat helps regulate body temperature and metabolism; its responsiveness declines with age in animal models, but human relevance and therapeutic applications remain under investigation. Readers should consult a healthcare provider for personal medical decisions.