Exercise vs. Nutrition

[SunsetRunner]

I have several friends that insist that they can pay less attention to their diet if they exercise their way through it. Only my opinion, but I don't think that is possible (or prudent). Their main goal is weight loss, not muscle mass. I just don't think a poor diet can be overcome by over-exertion. What's your opinion?

[Dominique]

"over-exertion" implies the amount of exercise is excessive. It is true that in most cases, it’s very difficult (though not impossible) to "out-exercise" a poor diet, so if the main goal is to lose weight, it makes sense to focus on your diet. This doesn’t mean exercising is pointless: it can definitely help create the deficit required for weight loss to happen, and it certainly has other benefits (health, fitness, well-being etc.).

[checking]

I think there are two ways to look at it: You can try to exercise your way though a poor high-calorie diet, or you eat a high-calorie diet to support the large amount of exercise that you enjoy doing. I enjoy walking in the mountains and average a bit above 30k steps a day (~14-15 miles, some of it indoors) and burn about 2000 exercise calories doing it. My BMR is calculated at 1800 cal, so I need to eat about 3800 calories just to maintain weight. I would call it a poor diet if I ate less. If I wanted to lose weight, I'd drop to about 3000 calories/day and continue walking/exercising the same. I guess this is what you call exercising through a poor diet.  Not from the way I look at it.

More practically, if you are trying to lose weight, you should not let you (average) caloric input get too much below your BMR. After that caloric differential (BMR + exercise - intake) is the important factor determining weight loss and, as a general rule to avoid metabolic disturbances, it should be limited to an (average) not much over 1000 calories/day (~2 lb/week).