This is the first part of a post I’ve been meaning to write for many months now, ever since the second annual Childhood Obesity Bay Area (COBA) Conference, held in February (I know, an embarrassingly long time ago – blame my job in consulting…). Since that conference, I’ve heard this same argument from multiple directions: the way we are currently thinking about the obesity crisis is flawed. Given the evidence, which I’ll describe below, we can no longer blame obesity solely on an imbalance of “calories in, calories out.” This message keeps hitting me from a variety of sources and I’m growing more and more convinced.

So what’s the answer instead? Why is obesity a growing issue? I can identify at least a few likely drivers of this growing epidemic (with the caveat that I am no scientist, this is based on what I’ve read):

1. The preponderance of refined carbohydrates in our diets today (and the loss of our common knowledge that carbs lead to fat cell growth) – all calories are not equal
2. The impact of industrial chemicals on our biologic systems and genetic expression
3. The impact of our diets (carbs, chemicals, antibiotics) on our microbiomes
4. …and who knows what else. I get the impression we have a lot left to learn about the inner workings of our digestive systems specifically and our bodies more broadly

I’ve procrastinated on this post for so long because it’s such a big one. There’s so much to cover and, to make it manageable, I’m going to split it into two, as well as quickly recap arguments others have made and provide links instead of explaining it all thoroughly myself. Bear with me.

(FYI the three main sources I’m drawing on are 1) Why We Get Fat by Gary Taubes, 2) a fascinating article called “The Obesity Area” by David Berreby, and 3) a talk given by Julie Guthman at the 2^nd annual COBA – sorry, no link for this one)

Why does the “calories in, calories out” paradigm not hold up?

Weight gain occurs when an individual consumes more calories than he or she burns, right? As a society we’ve internalized this logic so thoroughly that it’s become pretty hard to imagine it’s not true. But if that sentence tells the whole story, how can we explain the below?

1. Despite continued increases in obesity rates over the past ten years, we are steadily eating less calories (if you’re interested, read through the possible explanations for this disconnect in the article, they’re pretty creative:
   http://www.huffingtonpost.com/2013/03/07/calorie-intake-decreasing-consume-fewer-obesity_n_2824771.html)
2. In fact, there’s no indicative proof that caloric intake in industrialized countries has risen OR that activity levels have declined since 1980, as concluded in The Obesity Epidemic: Science, Morality, and Ideology by Michael Gard
3. Caloric intake does not significantly vary by racial groups or by income, despite differing obesity rates among these groups, according to the USDA study “What We Eat in America” (see average calories by race and by income; and yes the data are self-reported, but is it realistic that one group is mis-reporting calories by a great factor than another?)
4. In many low-income countries and low-income communities, obesity in adults coexists with chronic malnutrition in children, often within the same families (as described in the 2005 paper, “A Nutrition Paradox – Underweight and Obesity in Developing Countries”); if obesity is driven by too many calories, are we forced to conclude parents are gorging themselves while not feeding their children enough? That’s a tough one to believe…
5. There is a significant increase in infant obesity over the past few decades, which is difficult to blame on a lack of exercise or a deterioration of willpower (this study cites a ~74% increase in the prevalence of obesity with infants ages zero to six months old between 1980 and 2001)
6. Animals which are in contact with humans are getting fatter too despite rigidly controlled diets (e.g., for lab animals; this one is a fun one, pretty out-there but shows there are more factors which could contribute to weight gain than perhaps we currently recognize: http://www.sciencedaily.com/releases/2010/11/101124073900.htm)

Hopefully the above are enough to get you thinking about what really drives obesity. In Part Two, I’ll share potential alternative explanations for the obesity epidemic put forth by Gary Taubes, Julie Guthman, David Berreby, and Michael Pollan.

Stay tuned…