Does exercising make one gain weight?

When someone exercises one eats more so should one exercise or just eat less?

It makes you gain muscle, which, being more dense than fat, weighs more, it will seem like you are getting heavier. You will lose body fat if you eat less calories than you use in one day.

You eat more but get slimmer - muscle may weigh a lot but it looks a whole lot better than fat! So don't worry about eating a bit more (sensibly) when you exercise.

I was reading today that muscle build-up also actually prevents fat gain, so as you get a bit muscley from exercise it actually fights against fat production. I think I can see how that's working in my own experience, so I'd definitely go for the exercise option instead of the eating less one.

you will gain muscle, but lose fat. Eating a lot of healthy foods will fuel your body for a good workout. Your body needs to eat so it has something to run off of, and your metabolism will increase overtime. Be sure to eat breakfast. If you are just wanting to slim down and tone up your body you can work out with small weights... 5lbs or less.