Exercise reduces hunger in lean women but not obese women

ANN ARBOR, Mich.—Exercise does not suppress appetite in obese women as it does in lean women, according to a new study.

"This [lack of appetite suppression] may promote greater food intake after exercise in obese women," said Katarina Borer, a University of Michigan researcher in the Division of Kinesiology, and lead author of the study. "This information will help therapists and physicians understand the limitations of exercise in appetite control for weight loss in obese people."

The results will be presented today (June 17) at The Endocrine Society's 90th annual meeting in San Francisco.

Borer and her co-authors sought to better understand how changes in body fat level influence appetite and a hormone called leptin, which in animals curbs appetite when body fat increases. When leptin levels rise, it supposedly shuts off appetite and motivates physical activity to burn calories. However, as obese people become heavier, their leptin levels rise, but they become resistant to the actions of this hormone.

"The hormone doesn't do the job it's supposed to do," Borer said.

Borer's group studied 20 postmenopausal women: 10 lean and 10 obese women. The women ate three weight-maintenance meals a day while participating in three experiments on three separate days. During one experiment they did not exercise.

In the other two experiments the women exercised on a treadmill in the morning and the afternoon. They burned 500 calories each time. These two experiments differed by exercise intensity. One involved walking at high intensity, or 80 percent of maximal effort, for 7.5 minutes, with 10-minute rest periods between 10 walking sessions. The other experiment was half as intense (40 percent of peak effort) and involved walking for 15 minutes and resting for 5 minutes.

Every hour and before each meal, subjects recorded their appetite level on a 10-point scale ranging from not at all hungry to extremely hungry. Blood samples were collected every 15 to 60 minutes for hormone measurements.

"Obesity interferes with leptin's detection of exercise energy expenditure and with appetite suppression," Borer said. "Obese women perhaps need to consciously watch their calories because some of the hormonal satiety [fullness] signals don't seem to work as well."

http://www.ns.umich.edu/htdocs/rele...ory.php?id=6616

Jonny Bowden was saying in one of his books that when he hooked people up to a metabolic cart at a NY gym where he used to work, the amount of calories they actually DID burn for exercise varied radically. Literally, people would do the same exercise and not burn anywhere near the same amount of energy.

So it makes me wonder, without a metabolic cart, how any research study like this can say, "group X exercised and burned off 500 calories." They don't really KNOW that.

Exactly what i was thinking How do they KNOW?

I know that exercise only made me more hungry before I started low carbing.

This is one the things that always gets me in trouble with people who believe in the weight-reducing effects of exercise. Numbers on cardio equipment are a joke. Numbers on a heart rate monitor are nearly always less for the same exercise, and a heart rate monitor is simply doing a calculation, too. A metabolic cart is the *only* way you know how many calories you burn.

LC, HC or in-between carb -- aerobic exercise makes me hungry. What utterly kills me about it is that I can do it, be hungry, force myself to NOT eat and see absolutely no difference in rate of weight loss. And if I do eat to satiety after exercise I do not lose anything at all.

I'm all for moving but please don't tell me that exercise suppresses *my* appetite or helps *me* lose weight.

I walk my dog every day. Brisk walk, below cardio levels, that I enjoy. If someone wants to call it exercise that's fine by me, but in my view it's simply normal activity that makes me (and the dog) feel good.

So...What made the lean women lean and the fat women fat? And what's a "weight-maintenance meal"? Is it a high carb diet? Well let me tell you a story about how hungry that kind of meal makes me.

From a purely selfish standpoint, I'd like to see a lot more research into the post-obese. And pre-obesity, if possible. I don't have any trouble believing the basic premise from the above article - that the lean are more responsive to leptin than the obese. Duh. We know that already.

I'd like to know if it's the chicken or the egg. Did the women who didn't respond to leptin start out with a lowered leptin sensitivity and that's what led them into obesity? And/or, if these obese women with the lowered leptin sensitivity lost weight, would they become more leptin sensitive?

That has been my experience as well. When I was much, much heavier, exercise never stimulated me. Actually,to be blunt, it made me feel terrible and weak.

It never got better; it always made me tired and depressed. Once I started low-carbing (and lost weight) exercise has been more like they always said it would be. I have an appetite for it, now, not a dread.

I definitely buy into the belief that you should lose weight first, then bring in exercise as it works for you.

It's the egg but it's farther back than that. What made those women resistant to leptin? Could it be the low fat high carb diet that made them fat which in turn made them resistant to leptin? That would work in my book. The alternative is that they eat more so they grow fatter so they become resistant to leptin so they eat more so they grow fatter and round we go without knowing what's the cause and what's the effect.

It is the same to me!!!! Now when I go to gym I burn the few carbs I eat and I start almost to burn fat very very fast ( deep ketosis) and I feel without hunger !!!!

That is my experience with exercise, especially cardio. It makes me tired, weak, grumpy and HUNGRY! And the hungry effect lasts for 2-3 days.

It didn't get better the last time I did LC (for 6 months, lost 25lbs which was all I needed to lose then). But I still have hope that this time it might be different.

And I agree there's a real chicken-egg question here, about leptin, etc.