Correlation is not causation: “obesity epidemic” and animal product consumption

Americans have been drinking less milk since the mid-1970s, especially whole milk.  AT THE EXACT SAME TIME THAT THE OBESITY RATE INCREASED. Around the same time, chicken consumption went way up and red meat consumption went down. Chicken consumption has been trending down recently, though. OMG THE REASON OBESITY RATES HAVE LEVELED OFF IS WE RESTORED THE CHICKEN-BEEF BALANCE! Per capita egg consumption has fallen from 320 a year in 1967 to 233 a year in 1991 (244 in 2004). Per capita potato consumption has stayed about the same (going up 122 lbs/year in 1970 to 145 lbs/year in 1996, then falling back to a projected 112 lbs/year in 2011 and 2012).  And during this same time period, high fructose corn syrup consumption increased.

Only one of those changes in American diets has faced much blame for the increase in BMIs, though. Maybe that has something to do with how the foods that have decreased are considered “bad” foods according to mainstream nutrition advice. (As opposed to paleo/Atkins/Taubes advice.)

This doesn’t necessarily mean that high fructose corn syrup is not connected to the change in BMI, or that milk, egg, or meat consumption is. This study in particular makes a pretty good case for a connection between HFCS and an increase in body fat. OTOH, not everyone agrees. One of the authors defends the paper at Grist. Paul Ernsberger seems to be a pretty smart guy, and he thinks it’s possible.

On the other hand, at a minimum this data means that an increase in per capita milk consumption, whole milk consumption, egg consumption, or red meat consumption is NOT responsible for the “obesity epidemic”, because consumption of these things has not increased, it’s decreased. (Of course, this doesn’t say anything about their effects on, say, cholesterol.) Whole milk may have more calories per volume than skim, but what evidence we have indicates choosing skim instead of whole milk doesn’t affect BMI. There’s no particular reason to think that consuming the abomination known as nonfat yogurt will lower anyone’s BMI. Bu with the way things are divided into “good foods” and “bad foods” and the moral panic about how we’re eating (especially all those fast food burgers and fries!) it’s easy to be surprised by this information.

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3 Responses to Correlation is not causation: “obesity epidemic” and animal product consumption

  1. The Real Cie says:

    I’ve had some thoughts on the increase in body size (height as well, not just weight) and earlier puberty. I believe that all the hormones that end up in the food supply may have something to do with it. Just a thought. Whatever the case, the whole blame and shame game does nobody any good. How are the tactics used on “The Biggest Loser” (deliberate dehydration to weigh less at weigh ins, exercising to the point of puking) any healthier than swallowing tapeworm eggs to make oneself thin?

    • The tactics on TBL are just plain not healthy. “The Fat Chick” Jeanette DePattie has a couple of posts that go into more detail about it.

      WRT hormones in the food supply causing the increase in height and weight and earlier age of puberty, it’s hard to say. I don’t think we can rule it out, anyway. From what I’ve read, even lab animals (with controlled diets, so the amount they eat or type of food shouldn’t be different) have been getting fatter.

  2. sandrawhin says:

    Great post!
    I wonder what parallels there are between the timing of the ‘obesity epidemic’ and consumption of trans/hydrogenated fats.

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