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.

Putting Fat in Its Place

Have you ever thought about how contradictory some TV commercials can be? You see an ad for a restaurant that prides itself on its luscious pies, then the next commercial is about low-fat yogurt, or high-fiber cereal, or the local health club. With those mixed messages, no wonder it’s hard to do what’s best for you.


Actually, the reasons for avoiding the restaurant’s rich pies aren’t all that difficult to understand. Your body needs enough vitamins, minerals, iron, and protein to function properly. What your body doesn’t need much of are foods loaded with salt, sugar, and fat. The calories from those foods really do little to affect the body positively. Instead, they can contribute to increased blood pressure, and put added stress on the heart through extra weight.

It takes only 3,500 calories to equal one pound. This may sound like a lot, but they really can add up quickly. If you ate one 500-calorie piece of pecan pie for seven days in a row, if nothing else were altered in your diet or exercise program, by the end of that week you’d have gained a pound. And that’s the way they can start to add up.

Exercise to the Rescue

Exercise can help. It can put fat in its place by turning it into muscle tissue. What’s more, exercise can prevent extra calories from becoming extra pounds. It’s tempting to eat everything in sight when you’re hungry, and that can add up to calorie overload.

Calories are nothing more than a measurement of energy. Like a steam engine that uses coal for fuel, the body uses calories obtained from food as a source of energy. When it needs more energy, it uses more calories. Likewise, if there isn’t a big energy demand, those calories can be stored until needed. The body stores the calories it doesn’t use right away as adipose tissue, better known as fat.

An active, energetic person usually doesn’t have much extra fat because calories are continually being used for fuel. The classic legion of couch potatoes, on the other hand, probably has increased stores of calories, since, generally, their energy requirements are lower.

Facing the Fats

This all means that if you eat the same number of calories that you burn off, you won’t gain weight. But, if you eat more than your body can use, you’ll notice a weight gain.

Everyone’s metabolism (the rate at which your body uses food) is different, so it’s difficult to compare calorie requirements between people. Some people gain weight easily even if they don’t overeat, while others may eat a lot and never gain an ounce. Age, sex, heredity, and physical makeup all figure into the total scheme of metabolism and weight control.

Older people, for example, may exercise daily and be very active. But they may not need as many calories because their metabolism might be slower. Young people, for the most part, need more calories, since their energy levels are higher and their metabolism is faster. Nutritionists recommend that girls age 15 to 18 should eat an average of 2,100 calories a day, while boys age 15 to 18 should have an average of 2,800 calories a day. But it is also important that girls not go below an average of 1,500 calories per day unless they are under a doctor’s supervision for weight loss. There is a limit to how much a person can cut back on calories and still be healthy.

Get Moving


Fitness experts have some simple advice when it comes to fighting fat and staying fit. They say that exercise and movement are simply the flip side of eating. It’s not enough to treat your body like a bottomless storage bin of stockpiled calories. That only translates into extra pounds and fatigue. These experts suggest that good health involves the total body, not just what is–or even isn’t–put into the mouth.

Interestingly, dieting alone isn’t the most effective method of dealing with extra weight. The problem with many diets is that they are just fads that quickly fade away and are easily forgotten.

Aerobic exercise such as swimming, biking, walking, and running can have a far more lasting effect than just maintaining fitness and promoting a healthy heart. These exercises use a lot of energy, so they burn calories faster. Research has shown that people who exercise regularly burn more calories than those who are inactive. So they are likely to be thinner and have less overall body fat.

There are also the added benefits of lower blood pressure, reduced stress on the heart, and a decrease in the amount of harmful blood fats like cholesterol. Your self-image will get a positive boost, too.

Certainly building a good exercise program into your daily routine is much better than having to constantly worry about what you eat every day. Not only that, if you know that you will be exercising the extra calories off, it won’t be necessary to feel guilty about eating an occasional burger with fries or a favorite dessert. And there won’t be the need to come up with an excuse for why the latest diet didn’t work. You will have discovered something that does!

What you get when you get moving

Want to start exercising but don’t know how long it will take to see results? Some benefits start almost immediately; others take longer. Here’s a time-line, prepared with the help of exercise physiologist John Duncan, Ph.D., a professor of clinical research at Texas Woman’s University in Denton, of the benefits of doing three 30-minute aerobic sessions each week. (If you work out longer or more often, your benefits will be even greater.)


week1Fitness: Expect about a 1-percent boost in your endurance (you’ll feel more energized), as well as a drop of about 1 beat per minute in your resting heart rate (which means your heart muscle is already getting stronger, pumping more blood with each stroke).

Weight: If you were at least 25 percent overweight before you started and are now on a sensible diet, count on shedding up to 2 pounds. For others, no discernible weight loss…yet.


Fitness: You’ll be up to a 4-percent increase in your aerobic capacity – the amount of oxygen your body is able to process and consume during exercise. (When you run up stairs, for instance, you won’t feel as out of breath as you used to.) Plus there’ll be a total drop of about 4 beats per minute in your resting heart rate. (A fit rate hovers between 50 and 70.)

Weight: Another 4 to 6 pounds will come off if you began 25 percent overweight and are eating right. Others will shed perhaps 1 to 2 pounds. Also, expect improved muscle tone.

Blood Pressure: If you started with higher than normal blood pressure and/or were overweight, you’ll see a total drop of 5 to 7 points in your systolic pressure (the top number, which measures the maximum pressure produced in the large arteries by each heartbeat), and a 1- or 2-point drop in your diastolic pressure (the bottom number, which measures the constant pressure maintained in the arteries between heartbeats). That’s a clear sign that blood is flowing more easily to your muscles and vital organs.


3months“At this point, it’s as if someone flipped a switch,” says Duncan. “The health-promoting changes really start kicking in.”

Fitness: Now, oxygen-burning capabilities will be a total of 10 to 15 percent higher. Your resting heart rate will drop, on average, another 5 to 7 beats.

Weight: If you started out 25 percent overweight and are eating right, you’ll have shed a total of 12 to 17 pounds. Others will see a more modest (perhaps 5- to 10-pound) loss. Muscles will now be a bit larger and more toned. To see more significant changes in muscle tone, add weight training.

Blood Pressure: You’ll be up to a 7- to 12-point drop in systolic pressure, and a 3- to 8-point drop in diastolic pressure.

Cholesterol: Perhaps you’ll see a slight reduction in total cholesterol levels, but more importantly, there will be a definite (3 percent) rise in “good” HDL cholesterol, vital for preventing plaque buildup in arteries. For every 1 percent rise in HDL levels, you lower your risk of heart disease by 3 percent.


6monthHere’s when you’ll feel the greatest gains in health and fitness, Duncan says.

Fitness: You’ll be up to a 15 to 20 percent improvement in your aerobic capacity. Your resting heart rate will have dropped a total of 10 to 15 beats per minute. Now, it’ll take you only 3 to 4 minutes to “recover” after a workout-more proof that you’re using oxygen more efficiently.

Weight: The formerly overweight can expect a total of up to 30 pounds off. Otherwise, the scale may not show much more of a drop – muscle weighs more than fat – but your pants will fit less snugly.

Blood Pressure: There will be a total reduction of 8 to 15 points in your systolic pressure, and 4 to 10 points in your diastolic pressure.

Cholesterol: You’ll see a 5 to 10 percent increase in HDL levels, often enough to change your readings from abnormal to normal.


1yearFitness: You’ll be 18 to 25 percent better at burning oxygen than when you started. For even more improvement, work out longer and/or more frequently.

Weight: Because it now takes fewer calories to maintain your body weight, your weight will remain about the same. To lose more, exercise more or decrease your calorie consumption.

Blood Pressure: Expect a total drop of 8 to 18 points in your systolic pressure, and up to 10 points in your diastolic pressure.

Cholesterol: HDL levels will have increased a total of 12 to 15 percent – enough, usually, to extend your life expectancy by a couple of years.