&gt; The problem some people have is when exercise increases their appetite to the point where they continue consuming too many calories.<p>It&#x27;s very difficult to overeat <i>good</i> exercise with <i>good</i> food.<p>If your idea of exercise is to sit around at the gym for an hour and do a couple of lifts, that&#x27;s not gonna help. I&#x27;ve seen a lot of that. People go there for two hours, but only get like 15 minutes of real exercise done.<p>But if your idea of exercise is to go on a 10k run, or doing a boxing class for an hour ... well those are going to burn around 700 calories. That&#x27;s a lot of calories for someone who&#x27;s supposed to eat 2000 a day.<p>Eating 2700 calories (your normal 2000, plus the 700 you burned) is <i>hard</i> if you&#x27;re not eating cake and stuff. I personally struggle every day to keep my weight from plummeting because the amounts of food I have to eat are astounding. Especially on the days when I do a 30km run (that burns 2500 calories).<p>Honestly, it&#x27;s taken me over a year of sustained effort to train my metabolism to digest these sorts of quantities of food.<p>And yes, I am an edge case. My point is that you <i>can</i> outrun a bad diet. It will take a lot of running though.<p>PS: the biggest mistake people make is thinking that weight == health. You can be skinny and still super unhealthy.