Brown fat cells provide hope for obesity research

| Contributing Reporter

Not all fat cells mean weight gain.

National researchers in cell biology have identified proteins that turn normal skin cells into brown fat cells, which use energy to generate heat.

“Energy only gets burned when your heart beats or your muscles walk up a flight of stairs or when you breathe,” said Clay Semenkovich, chief of the division of endocrinology, metabolism and lipid research at the Washington University School of Medicine.

Brown fat cells do not store energy. They burn it without carrying out a function, such as beating the heart or walking, Semenkovich said.

Until recently, scientists believed that only animals and human babies had brown fat cells. But researchers discovered brown fat cells in adults when PET scans showed higher rates of glucose metabolism in patients who had been waiting in cold waiting rooms at their doctors’ offices.

Brown fat evolved to help people and animals in cold environments stay warm, Semenkovich said.

“People were freezing in the waiting rooms, and they were actually turning on brown fat,” he said.

The presence of brown fat cells in human adults carries implications for obesity research.

“People who are overweight have much less active brown fat,” Semenkovich said.

Researchers at Harvard engineered skin cells from mice and humans to become brown fat. This technology requires further research, though, before scientists can test it on humans.

“There’s always a disadvantage to tricking the body into doing things that it probably should not do,” Semenkovich said.

With brown fat, that disadvantage stems from the heat that the cells release. The excess heat could lead to dangerous and possibly deadly fevers in humans.

In the early 20th century, a chemist identified 2,4-dinitrophenol, a chemical that produced the same effects as brown fat cells.

“At one point somebody estimated that there were perhaps 500,000 people who had taken doses of this industrial chemical,” Semenkovich said. “It really did make them lose weight, but it also made them show up in emergency rooms with such dangerously high fevers that they died.”

Brown fat cell technology will require extensive research into controlling heat release.

“I want a therapy for people who are morbidly obese…but we’re going to have to be very careful about the way this is done or we’re going to cause a whole new set of problems,” Semenkovich said.

Weight loss research has implications for nutrition as well. Connie Diekman, director of University nutrition and former president of the American Dietetic Association, sees students on campus attempting to lose weight by changing their food intake and exercising.

“What many students get caught up in, though, is it doesn’t happen as quickly as they want, so they wonder about the fast loss, whether it’s the pills, whether it’s the diet, whatever it might be,” Diekman said.

Diekman said that while obesity research is essential to provide an understanding of metabolism, the public should approach weight loss techniques cautiously.

“You want to follow guidelines that are based upon what we know,” Diekman said. “Don’t change every time a new research study comes out.”

Currently, the scientific evidence shows that food changes are the proven method of losing weight.

“Physical activity alone will not do it,” Diekman said.

Diekman works with chefs on campus to create healthy food options for students. She also works to educate the University community on healthy food choices by writing informational brochures placed on the tables at dining locations such as Wohl Dining.

Sophomore Stephanie Trimboli finds that eating healthily on campus is “easy if you want to,” but she does not see much evidence of the administration’s attempts to educate students on healthful eating choices.

Despite nutritional guidelines, the implications of new weight loss research remain appealing to the public.

“It’s so seductive to people to be able to take something that will solve their problems without having to exercise [or eat less] that someone will always wind up doing it,” Semenkovich said.

  • Olivier Boss, PhD (energy metabolism researcher)

    It is important to keep things in perspective.

    Increasing energy dissipation by brown fat (thermogenesis) will:

    1. Not cause a fever. Body temperature is tightly controlled, and fever is a mechanism involving an increase in body temp. setpoint in response to an immunological challenge (e.g. infection). Physical exercise causes an enormous (several fold) increase in heat production, and it does not cause a fever. Heat is disspated in the sweating process. Activation of brown fat can be achieved in animals (rats, mice, dogs, hamsters), and it induces weight loss and NO FEVER.

    2. Not cause that big of an increase in heat dissipation and sweating as a ca. 20%-30% increase in energy dissipation (by brown fat activation) will be very significant on body weight on the long run BUT it is very minor compared to the 500%-1,000% increase in heat production-sweating taking place during moderate exercise.