What Causes Weight Gain Is Different from What Associates With Weight Gain
What causes weight gain? Ask the typical obesity researcher or dietitian, and you'll get an answer that's ultimately derived from the 1st law of thermodynamics, the principle from physics that tells us that energy in a system must be conserved. These experts will tell you that:
Energy Stored as Fat = Calories In - Calories Out
Thus, when you take in more calories than you burn off via exercise and metabolism, you'll gain weight. This is obviously true, they'll say, since the 1st law of thermodynamics must hold.
But what's not so "obviously true" is the direction of cause and effect in this equation. When we overeat (take in "too many" calories) or remain inactive (burn off "too few" calories), does that really cause obesity; or could it result from obesity? Maybe, as the Lipophilia Hypothesis tells us, when we accumulate too much fat in the fat tissue, something happens in our bodies to drive us to eat more calories and/or burn off fewer of them. Maybe that is what causes weight gain.
Study after study shows a strong correlation between inactivity and weight gain. A strong correlation also exists between 'increased appetite' and weight gain. But as any logician would tell you, correlation does not imply causation.
Here's science journalist Gary Taubes, one of the staunchest defenders of the Lipophilia Hypothesis, who writes in the magazine New Scientist that "the calories we consume must either be stored, expended, or excreted. If we are getting fatter, we must be taking in more energy than we are giving out: we are overeating. But this does not tell us in which direction the arrow of casualty is pointing. Do we get fat because we overeat, or is some regulatory or hormonal phenomenon driving us to fatten and in turn causing us to overeat?"
The moral of this essay is: don't let public health authorities who claim that inactivity and overeating cause obesity fool you. Sure, they're associated. Sure, there is a correlation. But that does not resolve the debate between Caloric Balance and Lipophilia.
We've spent billions of dollars over the course of decades studying what causes weight gain. During that time, we have been unable to clearly identify either overeating or inactivity as a cause of obesity. That should tell us something. It should tell us that the Caloric Balance Hypothesis -- the idea that 'calories count' -- is almost certainly incorrect. The failure to find data that convincingly support Caloric Balance should be a giant flashing red light saying "stop researching this idea and find a different hypothesis!"