If you are one of the millions of overweight Americans trying to slim down, fat is fat when you’re trying to squeeze into a pair of jeans or climb a flight of stairs without huffing and puffing.
But to researchers all fat is not equal — so-called brown fat helps regulate body temperature and burns more energy than white fat. People have both types of fat but usually a lot more white fat. It’s the white fat that accumulates around the belly and that’s associated with fat consequences, such as increased risk for diabetes.
Obesity and diabetes researchers may have landed on a way to make white fat behave more like metabolically active brown fat: cold temperatures.
“Just by changing the thermostat from 74 to 68 degrees Fahrenheit ... that was sufficient to increase the energy expenditure by about 6 percent,” said Dr. Francesco Celi, chairman of the Division of Endocrinology and Metabolism at VCU Medical Center, explaining the results of a series of studies on which he was lead or co-lead researcher.
“What we demonstrated is that with just minimal change in terms of temperature overnight was sufficient to increase the amount of brown fat,” Celi said.
Celi led the study while a staff clinician at the National Institute of Diabetes and Digestive and Kidney Diseases, a division of the National Institutes of Health. At Virginia Commonwealth University, he is continuing to look at how those discoveries can be turned into therapies for obesity and diabetes.
In the brown fat research, volunteers spent nights over four months in a metabolic chamber, a room that allows for precise measurement of oxygen breathed in and carbon dioxide exhaled — in order to determine energy expenditure or metabolism. Researchers raised and lowered the temperatures in the chamber and measured the effects on the study volunteers.
“Not only can we increase the brown fat mass, but this type of intervention generates an improvement in glucose metabolism,” Celi explained, referring to the lowered temperatures. People with diabetes have impaired glucose metabolism.
The improvement was completely negated, however, when the temperature was raised.
Still, the study proved a principle: that brown fat can be manipulated, Celi said.
VCU is constructing a metabolic chamber at a cost of about $1 million to allow for similar kinds of studies. The chamber is expected to be completed in September, and it will be available to researchers universitywide and at other institutions, Celi said.
“When you look at obesity and when you look at diabetes, they are meshed. And when you look at them collectively, I would say they represent the biggest health care dilemma of our time,” said Dr. Lori Sweeney, an endocrinologist and Celi’s colleague.
“In the Southeast there is a clustering of obesity. There seems to be a susceptibility factor in the Southeast. In fact the (Centers for Disease Control and Prevention) estimates that 1 out of every 3 adults in the southern eastern portion of our country meets criteria for at least overweight,” said Sweeney said, showing a map of the Unites States during a presentation last week to members of the local chapter of the American Diabetes Association. Celi and other VCU scientists talked about their work at the research briefing.
Health officials have been sounding the obesity and diabetes alarm for years. Almost 9 percent of adults in the United States have been diagnosed with diabetes, up from 3.5 percent in 1980. About a third of U.S. adults are obese.
“Our health care system simply cannot sustain the growing number of people developing diabetes,” said Ann Albright, director of the CDC’s Division of Diabetes Translation, during a joint media briefing in March with the head of the American Medical Association as they announced a new initiative called Prevent Diabetes STAT, with STAT standing for screen, test, act today.
The program emphasizes identifying people who are pre-diabetic — and getting them to make changes such as exercising more and losing weight — to reduce their risk. Research has shown that by losing just 7 percent of body weight, an overweight person reduces risk for diabetes.
“We cannot stay on the trajectory that we are on,” Albright said.
In Virginia, 900,000 people have been diagnosed with diabetes, said Richard Blackwell, chairman of the Central Virginia Leadership Board of the American Diabetes Association. An additional 2.2 million have pre-diabetes, or blood sugar levels that put them at risk of developing diabetes.
Celi said the studies on brown fat and temperature point to other areas ripe for study.
“If the results we have hold true, that could be also important in delivering messages in terms of public health, whether we need to be a bit more careful in how we manage our environment,” he said. “We can try to predict or study how much the manipulation of our environment can affect our health.”
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