Burning Calories While Inactive: Evidence That a Lack of Exercise Does Not Lead to Weight Gain

KEY POINT: Inactivity does NOT appear to lead to weight gain over the long term.

It's easy to believe in this idea. After all, we see a correlation between obesity and sedentary behavior. Just go to the mall food court and see who is burning calories. Who takes the stairs and who uses the escalator. Obese people are obviously lazy and/or out of shape. This is the conventional wisdom. And it's hard to see how anyone in his right mind could argue that physical inactivity would not lead to weight gain.

But, in fact, the evidence supports this assertion, amazingly. It turns out that sedentary behavior and obesity are definitely associated, but inactivity appears to be a consequence, not a cause, of being overweight.

This is a hard pill to swallow. It goes against everything that our intuition and our culture tell us about the importance of burning calories. So where is the evidence?

Here's some:

1. "Contribution of a sedentary lifestyle and inactivity to the etiology of overweight and obesity: Current evidence and research issues."

This is from a roundtable consensus statement published in November 1999, in which scientists assessed data from a variety of "ecological, cross sectional, and prospective studies that have assessed physical activity and dietary intake and the relationship to body weight."

The researchers don't exactly offer a glowing endorsement of the idea that burning calories via exercise prevents weight gain or that inactivity causes it. Consider this nugget:

"There is some evidence that a high proportion of dietary fat and low levels of physical activity may increase the likelihood of weight gain. However, even the most comprehensive studies are unable to account for more than a small proportion of the... variance in weight gain, so it is difficult to easily assess their relative importance."[1]

In the conclusion, the authors reiterate that inactivity is associated with obesity but the data are too weak to say what's causing what.

That passage may sound a little dry. But think about what it's saying! We've had a hypothesis for over 50 years that being inactive -- sitting on the couch -- will make you fat and that, conversely, going to the gym every day and burning calories is going to make you thin. But these authors tell us that, when you look at the actual data, we cannot find proof that physical inactivity causes obesity. This is a tremendous problem for the Caloric Balance Hypothesis -- and for anyone who wants to argue that "calories count."

2. And there is more of this stuff. Here's another, relatively randomly selected article from the American Journal of Clinical Nutrition, 2008: 'time spent being sedentary and weight gain in healthy adults: reverse or bidirectional causality'

The lead author concludes:

"the results show that although sedentary behavior does not lead to obesity, obesity and weight gain can lead to sedentary behavior." (bold added)[2]

This supports the idea that inactivity does not cause us to get fat but rather that inactivity is a consequence of getting fat, which is exactly what Lipophilia tells us.

3. For a plethora of other studies and a lengthy discussion about why inactivity and a failure to burn calories while exercising does not lead to weight gain -- as we've been told it should -- read Gary Taubes' book Good Calories, Bad Calories. In particular, check out chapter 16, 'Paradoxes' (271 to 291)[3].

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