Indulge in these tasty treats to give your metabolism a jump-start:Apples keep you fuller for longer Celery contains largely undigestible cellulose and water for a low-calorie snackBroccoli keeps your metabolism tuned, especially as you grow olderOats contain fat soluble fibre that not only fill you up, but also give you a lot of energyBrown rice keeps insulin levels balancedDark chocolate decreases the prevalence of cortisol, which is the stress hormone responsible for encouraging the body to store fat Grapefruit decreases insulin levels after eating to burn calories Garlic balances lipid levels to support blood sugar metabolismGreen tea promotes fat oxidationBerries help block digestive enzyme activity of some starches and fats