HOW DOES ONE LOSE WEIGHT THROUGH EXERCISING?
To lose weight, add variety to your fitness routine, and most importantly, combine muscle strengthening workouts with cardio training fitness activities. On the one hand, muscle strengthening will help to raise your body's metabolism, which means your body will burn more calories while exercising and while at rest. On the other hand, cardio training will trigger lipolysis, that is, the consumption of fat mass as energy fuel. Ideally, you should do a 1 hour workout session (50% muscle strength and 50% cardio) 3 times a week.
Don't forget to eat a healthy, balanced diet (1/3 each of proteins, vegetables, and carbs). Eat fruit to give your body plenty of vitamins, and cut out snacking between meals. If you're consuming more calories than your body needs (an average of 2000 calories a day for women and 2500 for men), you will have a hard time making up the difference through burning energy in your workouts. Exercising does not mean that you can eat more fat without weight gain. Exercise on its own is not an excuse to give in to your appetite for treats. If you want to slim down, you have to curb the excess.
So there you have it — it is possible that your body will gain weight as you do sports. This is explained through an increase in your body's muscle mass, in other words, the growth of your muscles. This doesn't mean you're not losing fat mass, but rather that your body is rebalancing itself. To get thin more quickly, go for the winning one-two punch: muscle strengthening + cardio training. Lastly, remember that a rich or fatty diet can negate your efforts to lose weight. So at meal times, make "moderation" your motto!