September 08, 2008
Gene Causes Obesity At Low Exercise Level

You might want to calculate your calories burned per mile walking at different speeds if you are having trouble fighting your weight. If you've got the wrong copy of a gene called FTO one solution is to become an Amish farmer to get the exercise you need to control your weight.

High levels of physical activity can help to counteract a gene that normally causes people to gain weight, according to a new study by researchers at the University of Maryland School of Medicine. They analyzed gene variants and activity levels of the Old Order Amish in Lancaster County, Pa., and found that the obesity-related FTO gene had no effect on individuals who were the most physically active.

"Our results strongly suggest that the increased risk of obesity due to genetic susceptibility can be blunted through physical activity," the authors conclude. "These findings emphasize the important role of physical activity in public health efforts to combat obesity, particularly in genetically susceptible individuals." The results of the study are being published in the Sept. 8, 2008, issue of the Archives of Internal Medicine.

Soren Snitker, M.D., Ph.D., the senior author and an assistant professor of medicine and pediatrics at the University of Maryland School of Medicine, says, "Our study shows that a high level of physical activity can 'level the playing field,' equalizing the risk of obesity between those who have copies of the FTO gene variant and those who don't."

The FTO gene recently has been linked to obesity and increased body mass index, or BMI, in several large-scale studies. More than half of all people of European descent have one or two copies of a variation of this gene, British scientists reported last year. Individuals with two copies of the gene variant are on average 7 pounds heavier and 67 percent more likely to be obese than those who don't have it.

We are not adapted to industrialized environments. Though not everyone does equally poorly in low exercise lifestyles. Therefore it is not surprising that scientists can find specific genetic variations that make some more or less adapted to less physical activity.

The more active among the Amish are known to burn a lot more calories than the vast majority of people who live in industrialized countries. Though they are not all intensely physically active since they do not all work in the same occupation. Even different kinds of farming introduce different levels of physical activity.

University of Maryland researchers found this same link between variations of the FTO gene and increased risk of obesity in their study of 704 Amish men and women. But, in examining the gene in this unique group of people with a similar genetic background and active lifestyle, the researchers also found that high levels of physical activity helped to counteract the gene's effects. "Having multiple copies of FTO gene variants had no effect on body weight for people who were the most physically active, regardless of whether they were men or women. But in less active people, the association between the gene and increased BMI was significant," says Evadnie Rampersaud, Ph.D., the lead author and a former postdoctoral fellow at the University of Maryland School of Medicine who is now at the University of Miami Institute for Human Genomics. "This provides evidence that the negative effects of the FTO variants on increasing body weight can be moderated by physical activity."

You have to burn an extra 900 kilocalories per day in order to fully control for the effects of the weight-boosting FTO variant.

Participants were classified as having "high activity" or "low activity" levels. The more active people used 900 more kilocalories, or units of energy, a day, which translates into three to four hours of moderately intensive activity, such as brisk walking, housecleaning or gardening.

This isn't to say that a lower level of exercise wouldn't help. In fact, jogging 30 miles per week lowers the rate of weight gain but does not stop it entirely. Those 30 miles probably amount to about 120 kcal per mile or 3600 kcal per week. That falls short of the extra 7 times 900 kcal per day for these Amish or 6300 kcal per week. So maybe if you ran 52.5 miles per week that'd prevent weight gain. Um, I'm not up for doing that. If you want to save time running at 10 mph burns over 1000 calories per hour.

In another study a group of Old Order Amish in southern Ontario were found to walk about 5 times further per day than the average American. They had a very low rate of obesity too.

But burn calories they surely do, as his study in the January edition of Medicine and Science in Sports and Exercise demonstrates.

The 98 Amish adults Bassett surveyed wore pedometers for a week. The men averaged 18,000 steps a day. The women took an average of 14,000 steps.

The men spent about 10 hours a week doing heavy work like plowing, shoeing horses, tossing hay bales, and digging. The women spent about 3.5 hours a week at heavy chores. Men spent 55 hours a week in moderate activity; women reported 45 hours a week of moderate chores like gardening and doing laundry.

The obesity rate among the participants was 4 percent, as determined by body mass index, or BMI. The current obesity rate among the adult American population is a whopping 31 percent.

By contrast the average American takes about 3000 steps per day. A 200 lb person walking 3 mph can burn 70 extra kcals per mile as compared to sitting still. So you'd need to walk over 12 miles per day to equal the extra calories burned by a heavily active Old Order Amish farmer. You could walk at a brisk pace and cut your time down from 4 hours though or even jog. You could also weight train to build up your muscles in order to boost your rate of calorie burn while sitting still.

Share |      Randall Parker, 2008 September 08 05:42 PM  Aging Diet Weight Studies


Comments
Bisaal said at September 9, 2008 2:09 AM:

Do Amish consume vegetable oils?

Brock said at September 9, 2008 7:52 AM:

Not all exercise is created equal. Muscle cells have multiple energy pathways, and gene expression is different depending on which ones you use. Low-intensity stuff like walking and gardening can be healthful, but it does not promote weight loss. If you want to lose weight do powerlifting and sprints. Short, intense bursts of exercise upregulates calorie burn and triglyceride release for many hours afterward.

Jogging however is just bad for you. It's bad for your joints, is an inefficient form of movement, and relies on an oxidative metabolism that produces free-radicals more quickly than your body can deal with them (Lance Armstrong probably gave himself cancer; he produces free radicals which harm DNA at a much higher rate than normal people). Both walking and sprinting are better for you, either alone or in combination.

Mthson said at September 11, 2008 10:45 AM:

Reducing calories would probably work just as well for people with these genes.

Eating a balanced diet but making 50% of the consumed food volume mixed greens and other ultra-low calorie vegetables seems like a simple and effective solution.

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