"We figured out how obesity occurs," says William A. Banks, M.D., professor of geriatrics in the department of internal medicine and professor of pharmacological and physiological science at Saint Louis University School of Medicine. "The next step is coming up with the solution."
The scientists used mice to look at how leptin, a hormone secreted by fat cells that tells us to stop eating, gets into the brain. They found that in obese mice, high triglycerides, a type of fat in the bloodstream, prevents leptin from getting into the brain, where it can do its work in turning off feeding and burning calories.
"High triglycerides are blocking the leptin from getting into the brain. If leptin can't get into the brain, it can't tell you to stop eating," says Banks, who is principal investigator and a staff physician at Veterans Affairs Medical Center in St. Louis.
"This is a big deal. We now know what is keeping leptin from getting to where it needs to do its work."
Paradoxically high triglycerides occur in both fat and starving animals and make the brain think the body's starving so the animal keeps eating, which makes it gain more weight.
"We figured out why the troops aren't getting to the front. There is all of this leptin in the blood but it isn't getting to the brain because triglyerides are impairing the transportation system.
"We feel that we now understand what part of the system is broken - why leptin isn't working. We have a better understanding of why people are becoming obese," Banks says.
The research points scientists to a new direction in solving the obesity epidemic.
"Lowering triglyceride levels may very well be a big part of the answer," Banks says. "This is a reasonable deduction that should be tested."
John Morley, M.D. director of the division of geriatric medicine at Saint Louis University and a co-investigator, agreed.
"If you lower triglycerides, you should theoretically help the body's own leptin to work better so people can get skinnier," Dr. Morley says.
Effective medications to lower triglyceride levels now are available, as is leptin, which can be injected into the body. Banks cautioned that the theory needs more testing before it is put into practice.
"All the bits and pieces are there but we have to be extra cautious," Banks says.
Solving the obesity problem has huge health implications for Americans. The nation's weight problem is fast overtaking tobacco use as the leading cause of preventable death. Obesity is linked to many chronic diseases including heart problems, several kinds of cancer and diabetes.
During the last decade, the obesity rate in America has doubled. Nearly two-thirds of U.S. adults are overweight or obese and 15 percent of young people between 6 and 19 are overweight.
Established in 1836, Saint Louis University School of Medicine has the distinction of awarding the first M.D. degree west of the Mississippi River. Saint Louis University School of Medicine is a pioneer in geriatric medicine, organ transplantation, chronic disease prevention, cardiovascular disease, neurosciences and vaccine research, among others. The School of Medicine trains physicians and biomedical scientists, conducts medical research, and provides health services on a local, national and international level. The division of geriatric medicine recently was listed among the top 10 programs in the country by U.S. News & World Report.