The body is a homeostatic organism. It tries to keep itself the same, to keep everything in balance. So when you cut back on your calorie intake, your metabolism will eventually slow down in response, which is bad for your dieting goals. Hard training, both in the gym and doing cardio helps to keep the metabolic rate stimulated. But another way is by varying your calorie intake over time. So for example your if you normally eat 3,200 calories a day and have gone on a 2,000 calorie diet. As your body begins to notice the calorie restrictions , it will slow down accordingly . But you don't need to actually eat as few as 2,000 calories every day you can average 2,000 calories. you do this by increasing calories for a day or so {say 2,600} dropping them way down {1,600} for a few days , then bring them back up to 2,000 calories. Additionally ,every week or so you can add a day of calorie intake at your previous level {3200} to further stimulate your metabolic rate. by dieting yhis way you will be ensuring that your metabolism is functioning at the highest possible level and therefore burning more calories in spite of your reduced calorie diet. Hope this helps someone and fill free to add anything else.