An Amazing Fat Loss Secret: Calories May Not Actually "Count"
If you're looking for a fat loss secret, no doubt you've come across numerous miracle drugs, pills, surgeries, herbal supplements, exercise programs, and the like. These magical cures almost all operate based on the idea that, to lose weight, we need to either eat less or get more activity. And it's true that people who lose weight take in fewer calories and/or burn off more calories. But the fact that weight loss associates with what's known as a 'negative energy balance' tells us nothing about what's causing that negative energy balance.
It could be that dieting and exercising make us thinner. Or it could be that, when we get thinner, we are driven to eat less and/or exercise more. This second explanation may sound like the 'the tail wagging the dog.' And if you've never heard it before, you might be tempted to reject it out of hand as based on a weird pseudo-logic. But the 1st law of thermodynamics -- the origin of both of these theories -- tells us that either one might be correct.
Weight loss and calorie restriction/increased activity may go hand in hand. But association doesn't tell us anything about causality. (For a closer look at the distinction between cause and correlation, check out this article.)
To figure out which of our two theories is most likely right, we need to look at evidence that either confirms or refutes their predictions.