Weight Maven

I’ve been meaning to get through Gary Taubes’ Good Calories, Bad Calories for a while now. But it’s an imposing book, chock full o’ science, which makes it a bit challenging, especially if you’re a lay person like me.

But Taubes’ work is very accessible in the video presentations that are available on the net. The video above is from medical grand rounds at Dartmouth-Hitchcock Medical Center in June 2009.

There’s also a longer version that Taubes gave in February 2008 at Stevens Institute of Technology.

Yes, they are longish. So while I encourage you to watch the video (I think the Dartmouth version is easier to watch; the slides are in a separate window), I’ve gone ahead and summarized some of Taubes’ points I found most interesting.

Note: The Dartmouth presentation is nearly an hour long. Given that, my summary necessarily omits more than it includes!! If you have questions, please refer to the video (hence the timestamps); I am sure that you’ll find the additional info/context useful.

Note too: All links (other than to Taubes’ videos) have been dug up by me and are added for additional reference.

The Obesity Epidemic

The subtitle for Good Calories Bad Calories is “challenging the conventional wisdom on diet, weight control, and disease.” What is the conventional wisdom? That obesity is explained by overeating and underactivity. Thus the conventional solution is “eat less, move more.”

In this world view, the “obesity epidemic” is typically explained by improved prosperity (e.g., Marion Nestle) and/or a toxic environment full of fast food restaurants etc. (e.g., Kelly Brownell). (6:42)

But Taubes notes that this hypothesis doesn’t adequately explain cases like:

• Fat Louisa: In the mid-1800s, the Pima were affluent and thin; in the early 1900s, they were living on reservations in extreme poverty with high rates of obesity. (7:45)
• Multiple studies from 1959-1981 showing obesity across world in various populations, most of whom are very physical active, no access to restaurant food, etc, i.e., not the kind of “toxic environment” Brownell refers to. (11:30).

He makes the interesting point (emphasis mine):

So the point of these studies is you could have high levels of obesity comparable to what we have in the United States today. … They do not eat too much because they can’t get too much to eat. … They’re refutations of our abundance, overeating, calories in/calories out notions.” (14:20)

Another interesting paradox (as well as another example of obesity and malnutrition existing simultaneously within a population) comes from Benjamin Caballero’s A Nutrition Paradox — Underweight and Obesity in Developing Countries (16:00):

A few years ago, I was visiting a primary care clinic in the slums of São Paulo. The waiting room was full of mothers with thin, stunted young children, exhibiting the typical signs of chronic undernutrition. Their appearance, sadly, would surprise few who visit poor urban areas in the developing world. What might come as a surprise is that many of the mothers holding those undernourished infants
were themselves overweight. …

The coexistence of underweight and overweight poses a challenge to public health programs, since the aims of programs to reduce undernutrition are obviously in conflict with those for obesity prevention.

Taubes questions the assumption with the calorie balance equation (where underweight and overweight are “in conflict”). Either these women were willing to let their children starve so they can be fat (which goes against maternal nature and is thus not likely), or the idea that obesity is about eating too many calories is incorrect.

Inconvenient facts

Taubes then goes on to cite several “inconvenient facts” related to the positive calorie hypothesis.

1) Efficacy of under-eating (17:30)

The biggest problem is that there is isn’t strong support for the idea that eating less works as a long-term treatment for obesity.

Taubes references this from The Handbook of Obesity (1998):

Dietary therapy remains the cornerstone of [obesity] treatment and the reduction of energy intake continues to be the basis of successful weight reduction programs …

[the results of such therapy] are known to be poor and not long-lasting.

2) Efficacy of exercise (19:20)

The next inconvenient fact is that exercise does not seem to reverse obesity. Taubes cites this from guidelines for physical activity (PDF) from the AHA and ACSM (2007):

It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling.

Note: just a few months after Taubes’ presentation, Time published its controversial Why Exercise Won’t Make You Thin.

3) Accuracy and counting calories (21:20)

Taubes then questions the whole premise that our weight is precisely regulated by calories in versus out. Keeping track of calories in is hard enough, it’s harder still to be aware of calories out. So Taubes question is if this is in fact true, why aren’t we all either obese or anorectic? Something more seems to be at work.

Note: See the video for the remaining “inconvenient facts” (genetics, sexual variations, and progressive lipodstrophy). They are supportive of Taubes’ thesis that fat accumulation is complicated and driven as much if not more by hormones, etc.

Laws of Physics

Taubes spends a bit of time discussing the laws of physics and the calorie balance theory (28:45). It’s a longish section, but it essentially boils down to the problem with using the first law of thermodynamics as it relates to the body and weight:

• there’s no arrow of causality
• energy in and energy out are not independent variables

Note: See Eades’ thermodynamics and weight loss for more info.

Alternative hypothesis

Taubes then outlines an alternate hypothesis for obesity (33:45):

• obesity is a disorder of excess fat accumulation
• primary defect is in the body, not the brain, and causes the excessive accumulation of fat
• overeating and inactivity are compensatory effects; they are not causes

Taubes sums this hypothesis as follows:

We don’t get fat because we overeat, we overeat because our fat tissue is accumulating excess fat.

Adiposity 101

Taubes spends the next section talking biochemistry and fat metabolism (43:50).

Please refer to the video for the details, but the very condensed version is this: fat cells make triglycerides out of fatty acids using glycerol-3-phosphate; the primary source of g3p is dietary carbs.

Interestingly, Taubes notes that fructose is the carb converted most efficiently into g3p!

[This is one] of several reasons that fructose is considered the most lipogenic carbohydrate and may be 90% of the problem. (48:10)

Note: See a more detailed write-up of this science as well as Lustig’s Sugar: The Bitter Truth for more on the role of fructose in obesity.

The Bottom Line

Taubes summarizes his alternative hypothesis this way (52:00):

• When insulin is secreted or chronically elevated, fat accumulates in the fat tissue.
• When insulin levels drop, fat escapes from the fat tissue and the fat depots shrink.
• We secrete insulin in response to the carbohydrates in our diet.

Note: Here is how Tom Naughton presents this information in Fat Head:

My two cents

Taubes is like the boy in the emperor’s new clothes. Everyone and their brother is looking at the “obesity epidemic” and doing their very best to ignore the role that dietary carbs play in fat accumulation.

Of course, all the carb defenders point to all of these cultures, like the Japanese or Kitavans, who have a high intake of carbs. And that is one of my tiny quibbles with his presentation: he doesn’t address the case where a high intake of carbs doesn’t lead to obesity or discuss the other factors that may be at play.

I also quibble a bit about his comment that the “primary defect is in the body, not the brain” tho I’m sure he’s technically correct that without the insulin resistance in the body, the brain-related appetite challenges couldn’t occur.

But Taubes point is really not asking to be to be assumed 100% right as much as ask people to consider an alternative hypothesis (emphasis mine):

If you want to prevent obesity and diabetes, and the chronic diseases that associate with it, you have to get the cause of obesity correct. You cannot have an entire nation and your public health authorities saying it’s caused by eating too much, because it’s not. (56:30)

This is my last quibble. I think his point is incredibly valid from a biochemistry point of view. There are people getting fat who aren’t eating too much, very likely because of the carbs in their diets.

But Marion Nestle and Kelly Brownell aren’t necessarily wrong. The ability to easily acquire the food that will exacerbate fat accumulation is very definitely tied to questions of wealth, toxic environments, and these days, to food quality and industrial production.

Unfortunately, all of is drowned out by the the “eat less, move more” crowd (see Eades’ low-fat diet cascade) — this is as much about dogma and politics as it is about science.