November 02, 2009
Low Exercise Not Cause Of Adolescent Obesity Spike?

This result strengthens my suspicion that high fructose corn syrup is to blame for the obesity epidemic.

Decreased physical activity may have little to do with the recent spike in obesity rates among U.S. adolescents, according to researchers at the Johns Hopkins Bloomberg School of Public Health. Prompted by growing concern that the increase was due to decreased physical activity associated with increased TV viewing time and other sedentary behaviors, researchers examined the patterns and time trends in physical activity and sedentary behaviors among U.S. adolescents based on nationally representative data collected since 1991. The review found signs indicating that the physical activity among adolescents increased while TV viewing decreased in recent years. The results are featured in the October 30 online issue of Obesity Reviews.

"Although only one third of U.S. adolescents met the recommended levels of physical activity, there is no clear evidence they had become less active over the past decade while the prevalence of obesity continued to rise," said Youfa Wang, MD, PhD, MS, senior author of the study and an associate professor with the Bloomberg School's Center for Human Nutrition and the Department of International Health. "During the recent decade, U.S. adolescents had greater access to TV, but significantly fewer of them watched TV for three or more hours per day. In addition, daily physical education attendance rates improved along with the use of physical education class in engaging in physical activity. However, there are considerable differences in the patterns by age, sex and ethnicity."

If less exercise isn't the cause of the obesity epidemic then what is? Some people say it is cheaper food. I'm skeptical. Lots of middle class kids had all the food they could eat in the 1960s. Refrigerators were full. Why did the obesity epidemic come later?

Share |      Randall Parker, 2009 November 02 10:20 PM  Aging Exercise Studies

Clarium said at November 3, 2009 12:12 AM:

I say it is cheaper food... the proles do not have time to cook and usually eat high glycemic index food with empty calories.

Brett Bellmore said at November 3, 2009 3:49 AM:

It might be an infectious agent, perhaps an adenovirus.

dlp said at November 3, 2009 5:35 AM:

When I was growing up in the '60s a Coca-Cola was a rare luxury. Today the kids drink soda pop like water.

Culture drives insulin.

random said at November 3, 2009 8:14 AM:

I think part of the issue is that our food is getting sweeter. My kids got some candy this year that was mostly sugar, but also contained aspartame for an extra kick of sweet.

I would be interested to see a historical study on the sweetness of our foods and drinks - not just sugar or high fructose corn syrup, but artificial sweeteners as well. Many people blame fructose, but artificial sweeteners also cause insulin spikes and weight gain.

PacRim Jim said at November 3, 2009 9:06 AM:

In the 1960s, we spend more than half the day outdoors, sitting only occasionally. Sitting for extended periods because of addiction to video games and the Web is an important factor.

Davemc said at November 3, 2009 11:44 AM:

I would give good odds that a big part of the problem is that prepared/processed foods have gotten comparatively cheaper and more prevalent. Fresh fruits and vegetables and high quality meats are comparatively more expensive than processed foods. It costs a lot more money to shop on the outside aisles of a supermarket than it does to shop in the center aisles.

Joe Y said at November 3, 2009 2:23 PM:

RE: DLP Not only was soda a rare luxury--which, by the way, had nothing to do with economic class, it was just a cultural attitude--but at least as important was that the portions were much smaller. Already, the 6.5 oz soda was rather uncommon, but the standard sizes were 10 or 12 ozs, with an occasional 16 oz bottle. The increasing portion size applies as well to fast food, bags and bars of candy, etc.

Larry said at November 3, 2009 3:41 PM:

It's not the lack of exercise that's making us fat, it's that we eat too much crap with HFCS at the top. Look what happened to Mexico after NAFTA. They went from a Country with low obesity levels to the second highest obesity rate in the World (after the USA) in less than 15 years. All due to cheap US farm products like HFCS.

profligatewaste said at November 3, 2009 4:51 PM:

Get on a treadmill for 30 minutes and you burn maybe 400 calories. It's too easy to overwhelm the effects of exercise with the caloric content of most junk foods.

In said at November 3, 2009 5:53 PM:

I think it definitely possible the declining quality (not so much the price) of the food supply is the major cause of the obesity epidemic. Another factor to consider is that obese women give birth to children that are more likely to be obese. There could be multi-generational epigenetic effects at play.

dlp said at November 3, 2009 7:36 PM:

"Another factor to consider is that obese women give birth to children that are more likely to be obese. There could be multi-generational epigenetic effects at play."

Or, alternatively, women who are obese due to excessive carbohydrate consumption foist on their children the same dysfunctional eating habits.

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