Friday, July 15, 2011

“Calories In vs. Calories Out is Irrelevant” says Gary Taubes

This is the theme of Gary Taubes’ new book “Why We Get Fat and What To Do About It”. He argues that the cause of obesity is not that one consumes more calories in than one expends calories out. The more scientific term for eating more and moving less is positive caloric imbalance, and rather than being the cause of obesity, he argues that positive caloric imbalance is the effect of getting fat.

This cause and effect is really hard for me to get my head around, as I suppose it is for most folks, at least before considering Mr. Taubes’ arguments or evidence.

For example, as mentioned in a previous post, in a study on mice those that had their ovaries removed got fat, either by eating more or if starved, then moving less. Estrogen, the sex hormone that’s produced in ovaries, was injected back into these mice, they ate less and they became leaner. When estrogen was removed, the mice stored more calories than they burned. Those stored calories in fat were not available for energy in the rest of the body, so the mice had to consume more food energy. When estrogen was replaced, the mice burn more calories than they stored, so energy was readily available and more food consumption was not necessary. The hormone was the cause of the obesity, and the caloric imbalance was an effect.

Another example given by Taubes is that children don’t grow taller because they eat more. They grow taller due to growth hormones. The growth causes a caloric imbalance, so they eat more. We don’t say that a 4’6’’ person is short because they ate too little, or that a 7’6’’ person is tall because they ate too much. Caloric imbalances are the result of growth hormones causing the body to grow and consume calories doing so. The effect is that children eat more.

Taubes is not saying that a fat person is not in positive caloric balance. Taubes is saying that a fat person is in positive caloric balance, but it’s irrelevant. It’s an effect of getting fat. So what causes us to be fat? I’ll give my understanding of Taubes’ hypothesis next.

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