5 Questionable Obesity Causes

The list of potential obesity causes seems to grow like kudzu. Why? Well, obesity develops slowly and improves slowly, if at all. Epidemiological studies provide ever more information about associations and some of these analyses are repeated so often that otherwise smart people start equating the link to a causal relationship.

Familiarity bias exerts even more of its deceptive influence because everyone eats and most everyone notices the weight of themselves and everyone around them. So people get used to making assumptions about cause and effect related to weight.

1. Overeating. Does overeating cause obesity or does obesity cause overeating? David Ludwig and Mark Friedman posed this provocative question in a New York Times op-ed yesterday. Like breathing, food intake is regulated by our bodies. Most people take it on faith that overeating is what causes obesity. But few people assert that heavy breathing causes poor fitness.
    
2. Restaurants. The association between eating out of home and obesity has been seen in multiple studies. The portion sizes and high caloric content of restaurant meals makes this association unsurprising. But should we be content to accept this association as one of cause and effect? Most intervention studies that target out of home eating behavior aim for an effect of better dietary choices, not for reducing the frequency of people eating out. So we have no data to say that less eating out leads to less obesity.
    
3. Inactivity. Increasingly, experts are coming to understand that obesity can cause inactivity just as much as inactivity can cause weight gain. It’s also pretty clear that increased activity might be useful for preventing weight gain and better health, but it’s not so helpful for promoting weight loss.
    
4. Artificial Sweeteners. Some bright people persist in promoting the idea that artificial sweeteners can promote a preference for sweeter foods and thus promote obesity. But they have no evidence to back it up. The evidence reviews to date have concluded just the opposite. Non-caloric sweeteners are a reasonable way to eliminate sugar, and thus calories, from your diet.
    
5. Failure to Breastfeed. The health benefits of breastfeeding are so well-established that most every woman who makes healthy dietary choices also chooses to breastfeed. Thus it’s easy to come up with studies that show a link between breastfeeding and a lower risk of obesity for children who were breastfeed. But a closer look makes it clear that this association is the result of confounding variables and publication bias. Authoritative evidence reviews conclude that breastfeeding offers many health benefits, but preventing obesity in children who are breastfed is not one of them.

 
Assumptions have a way of hiding in our decision making. It’s best to bring them out into the open.

Click here for the op-ed by Ludwig and Friedman, click here for perspective on restaurants, click here for more on inactivity and obesity, click here for more on artificial sweeteners, and click here for more on breastfeeding.

Lever, photograph © Leo Reynolds / flickr

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