I lost 60 pounds without doing a lick of exercise and kept it off for 10 years. In fact, I STOPPED exercising and focused on controlling the amount of food I ate and pounds started falling off. I don't recommend no exercise and have the cellulite that grew during that time to prove that point. Obviously it's necessary for good health, which makes me so glad I discovered cycling. Also good for toning and losing inches. However, for the purpose of losing fat, I have found it absolutely true that exercise is not "necessary". The more you exert yourself, the more fuel you need. The less you exert yourself, the less fuel you need. So whether you exercise or not, you have to learn to listen to your body's hunger and fullness signals.