A weighty response: research is focusing on the brain’s role in stimulating appetites

overweightBeing the butt of fat jokes is no laughing matter. Those who are seriously overweight can suffer from poor self-image, social ostracism, job discrimination and serious health risks from diabetes to heart disease. But for some individuals, shedding unwanted extra pounds can be a lifelong struggle: studies show that 95 per cent of dieters who lose weight regain all the lost pounds–and usually more–within three to five years. That once caused some people, including even some health professionals, to conclude that the obese were weak-willed or self-indulgent.

Now, however, new avenues of medical research are prompting scientists to rethink the causes of, and potential treatments for, obesity. Some of the most exciting discoveries focus on the role that chemical signals from the brain play in stimulating appetite. In some overweight people, those messages do not correspond with the body’s actual need for sustenance. “The appetite is an extremely complex system,” says Dr. Franco Vaccarino, an associate professor of psychology and psychiatry at the University of Toronto. “But if we can regulate, or normalize, an individual’s eating, then the weight will take care of itself.”

Until recently, many medical schools did not even teach nutrition and its role in promoting health. But mounting public concerns over obesity and other eating disorders helped change that. “There is now a tremendous amount of research going on,” says Harvey Weingarten, psychology professor at McMaster University in Hamilton. “It’s a very exciting time.” Weingarten, in fact, is the chairman of one of two major international conferences being held in Canada this month that illustrate the wide range of research currently being conducted into the psychology and physiology of weight management.

In Hamilton, from Aug. 16 to 20, members of the Society of Ingestive Behavior will present papers on topics ranging from the role of politics and culture in determining what people eat to whether a group of hormones known as peptides can be used to treat obesity. Immediately afterwards in Toronto, delegates to the International Congress on Obesity will examine an equally wide range of topics.

One exciting new area of obesity research stems from the strides made over the past decade in understanding the brain’s chemistry. While studying the role that a group of chemicals known as neurotransmitters–including serotonin, dopamine and norepinephrine–play in modifying mood, scientists noticed an unexpected side-effect: some clinically depressed patients taking the drugs to regulate the levels of neurotransmitters in their brain lost weight without even dieting.

neutrotransmiterThe research into the role of neurotransmitters is also being closely watched by pharmaceutical companies, who have not introduced a new anti-obesity drug in 20 years. Pharmaceutical researchers believe that the research eventually could lead to new diet pills that could help control weight with few unpleasant side-effects. (There are currently four amphetamine-like prescription drugs, marketed under six different brand names, currently available in Canada for weight control. But many doctors are reluctant to prescribe them because of the adverse side-effects, which can range from dry mouth and sleep disturbances to raised blood pressure.)

An easier-to-take diet pill could be worth billions of dollars because the market potential, after all, is vast: 25 per cent of Canadians and 30 per cent of Americans are considered obese, higher percentages than in the rest of the world. And health officials, who define obesity as being 20 per cent or more above ideal body weight–caution that those percentages are continuing to escalate.

The race to produce a new diet pill is already on. Eli Lilly and Co. of Indiana, for one, is currently conducting clinical trials in Canada and the United States into a drug named Lovan. It is a reformulation of the chemical fluoxetine hydrochloride, more widely known as the popular antidepressant Prozac. According to Cameron Battley, corporate affairs manager for Eli Lilly Canada Inc., in Scarborough, Ont., “initial reports are not conclusive.”

Still, the introduction of any new diet drug is bound to be highly controversial. Battley says that if Health Canada were to approve Lovan, it would only be available by prescription, and would only be recommended for the “morbidly” obese–those whose weight is a threat to their health. Critics counter that Prozac was introduced in 1989 as an antidote to clinical depression, but since then it has been used to treat relatively minor personality disorders. If a new diet drug followed a similar course, it could end up in the hands of those who merely wanted to lose 10 lb. by bathing suit season. There are also concerns about the potential long-term effects of any new drug.

Health experts add that because people are obese for different reasons, and that there are different types of obesity, no one solution will work for everyone. And even in those overweight individuals where brain chemistry is the problem, the neurotransmitters have an impact on so many different functions that it will be difficult to develop a pill that modifies eating alone. Says Vaccarino: “There is unlikely to be a magic bullet.” But as research continues, there is hope that there will soon be a new, sophisticated array of weapons in the battle of the bulge.