Exercise reduces hunger in lean women but not obese women

Jun 17, 2008

Exercise does not suppress appetite in obese women, as it does in lean women, according to a new study. The results were presented Tuesday, June 17, at The Endocrine Society's 90th Annual Meeting in San Francisco.

"This [lack of appetite suppression] may promote greater food intake after exercise in obese women," said Katarina Borer, PhD, a University of Michigan researcher 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."

Borer and her co-workers 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 fatter, 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 in lean people," Borer said.

In research funded by the National Institutes of Health, 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, for a total of 1,000 calories a day. 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.

Obese women claimed they were less hungry than lean women before meals and reported no appetite suppression during exercise, Borer said.

As expected, obese women had much higher leptin levels than in lean women, study data showed. But during intense exercise, obese women did not have reduced production of leptin, as lean women did. Only moderate-intensity exercise lowered leptin in obese women.

"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."

Source: The Endocrine Society

Explore further: ICU fatalities linked to after-hours discharge

add to favorites email to friend print save as pdf

Related Stories

Why some people are lean and others fat

Mar 07, 2011

With an abundance of food available, it’s not surprising that people are getting fatter. But why do some people remain lean? A Cambridge University scientist suggests that the reason is rooted deep in ...

'Yo-yo' effect of slimming diets explained

Jan 12, 2011

If you want to lose the kilos you've put on over Christmas, you may be interested in knowing that the hormones related to appetite play an important role in your likelihood of regaining weight after dieting. ...

Recommended for you

Obese British man in court fight for surgery

Jul 11, 2011

A British man weighing 22 stone (139 kilograms, 306 pounds) launched a court appeal Monday against a decision to refuse him state-funded obesity surgery because he is not fat enough.

2008 crisis spurred rise in suicides in Europe

Jul 08, 2011

The financial crisis that began to hit Europe in mid-2008 reversed a steady, years-long fall in suicides among people of working age, according to a letter published on Friday by The Lancet.

New food labels dished up to keep Europe healthy

Jul 06, 2011

A groundbreaking deal on compulsory new food labels Wednesday is set to give Europeans clear information on the nutritional and energy content of products, as well as country of origin.

Overweight men have poorer sperm count

Jul 04, 2011

Overweight or obese men, like their female counterparts, have a lower chance of becoming a parent, according to a comparison of sperm quality presented at a European fertility meeting Monday.

User comments : 0