Joslin Researchers Find ‘Good Fat’ Activated by Cold, Not Ephedrine

Both interventions — ephedrine injections and the wearing of the cooling vests — did result in the same number of calories being burned, Dr. Cypess noted.

“But we found that ephedrine was not using brown fat to do it,” he said. “This is the first time it has been found that ephedrine does not turn on brown fat.”

Both interventions had other effects on the sympathetic nervous system -- which activates the fight or flight response -- such as increased blood pressure, but those associated with brown fat activation were fewer, the study showed.

“Mild cold exposure stimulates (brown fat) energy expenditure with fewer other systemic effects, suggesting that cold activates specific sympathetic pathways,” the paper concludes. “Agents that mimic cold activation of (brown fat) could provide a promising approach to treating obesity while minimizing systemic effects.”

As a result of the findings, drug companies may find it easier to come up with agents that stimulate brown fat to help people lose weight, Dr. Cypess said.

One method may be simply to design cooling vests that people can wear to help them lose weight. A future study will have subjects wear the vests for several weeks to see what happens, Dr. Cypess said.

“Will they get the same health benefits they would have seen with several weeks of exercise? That’s the billion dollar question.”

The findings should also be of interest to heart researchers interested in the mechanisms of activation of the sympathetic nervous system, he added.

Co-authors of today’s study include Yih-Chieh Chen, Cathy Sze, Ke Wang, Jeffrey English, Onyee Chan, Ashley R. Holman, Ilan Tal, Matthew R. Palmer, Gerald M. Kolodny and C. Ronald Kahn. All are from either Joslin Diabetes Center or Beth Israel Deaconess Medical Center.

The study was funded by the National Institutes of Health.