>I run three miles a day

Which will burn somewhere on the order of 400 excess calories - about as much as a typical North American muffin (or two of the big cookies from Subway). But worse, your body was probably going to use most of those calories on something else (fidgeting, running a higher body temperature, other immune responses including inflammation) anyway, assuming that you haven't been gaining weight with your current habits. Exercise is healthy and reduces stress, but it just isn't effective for weight control. Humans are animals, and animals have on the order of a billion years of homeostasis technology behind them.

>eat reasonably healthy

Hardly anyone has any accurate picture of how much they consume, as measured in calories, except for those with actual explicit experience of measuring and accounting it.

If a pill happens to end up helping you eat an amount that lets you maintain a healthy weight, I'm all for that. But it's important to have your mental model properly calibrated.