To get back to your balanced weight, try giving your body what it needs rather than depriving or punishing yourself with harsh diet and fitness regimens.

1. Create the Message: Eat the Right Foods
A healthy diet might be the most important tool you have for balancing your metabolism. "Most people know enough to get the junk food and artificial ingredients out of their diet," says Galland. But improving your metabolism also involves "putting the good things in." Here's what you need.

Fiber The indigestible parts of fruits, nuts, whole grains, and vegetables sweep toxins from your body and slow the speed at which your body absorbs sugars from food. Both functions have a huge impact on your metabolism. The federal government recommends 25 grams of fiber a day for women and 38 grams a day for men. Foods like vegetables, beans, whole grains, and some fruits, especially berries, deliver fiber.

Healthy Fats Omega-3 fatty acids improve the metabolic function of every cell in your body, primarily by reducing inflammation. Increase your intake of fish, walnuts, and ground flaxseed while limiting your intake of pro-inflammatory omega-6-rich foods, like heavily processed foods as well as corn, soy, safflower, sunflower, and vegetable oils. Monounsaturated oils such as olive oil also have anti-inflammatory properties; make it your main cooking oil, says Hyman.

Fruits, Vegetables, and Spices Their phytonutrients -- carotenoids in carrots, curcumin in turmeric, anthocyanins in berries -- help "turn on" your body's metabolism at the cellular level and regulate hormones that help control appetite. These foods also contain high levels of antioxidants, which reduce inflammation. Center every meal or snack on fruits or vegetables -- totaling at least five to nine servings a day -- and use spices such as turmeric, cinnamon, and garlic liberally.

Friendly Foods Both Galland and Hyman also recommend paying close attention to foods that lead to bloating or other unpleasant symptoms. You probably know if you're truly allergic to a food, but it's possible to be intolerant and not realize it. Undetected intolerances can contribute to inflammation and hypothyroidism -- both of which spell trouble for metabolism.

Two of the most common food sensitivities are to gluten -- a protein present in foods like wheat, rye, oats, barley, spelt, and kamut -- and dairy. Hyman recommends removing them (or other foods you suspect you may be sensitive to) from your diet for at least a week to see whether your symptoms change.

2. Light a Fire: Exercise
When it comes to metabolism, the value of exercise "goes beyond the amount of calories you burn," says Galland. Resistance training builds muscle, and regular, sustained movement supports your thyroid, lowers inflammation, and improves the rate at which insulin can move blood sugar into your cells -- so there's more available as fuel and less sugar circulating in the blood to be turned into fat.

Any form of exercise helps, but you can increase your body's power to burn food calories (even when you're sleeping) by alternating periods of intense exercise with slower periods. Known as interval training, this exercise pattern "tunes up the mitochondria and increases your basal caloric burning," says Hyman. It doesn't matter what you choose to do -- walk, jog, bicycle, swim, or row. Exercise for one minute at nearly maximum capacity and then for three minutes at moderate capacity. Alternate for 30 minutes, two or three times a week, he says.

3. Clean Up Your System: Sweat
Pesticides, chemicals from manufacturing, and metals such as mercury and lead from air, water, and food circulate in the blood and wind up in body fat. In the blood, these toxins sabotage the body's main metabolic regulator -- the thyroid gland. (Another toxin accumulator might surprise you: rapid weight loss. When you burn fat, the toxins it stores enter the bloodstream.)

The solution: Sweat. Your body excretes toxins and waste in perspiration. "Not sweating is like not going to the bathroom," says Hyman. Regular exercise should make you sweat, but so will saunas and hot baths. Losing weight gradually -- not crash dieting -- will also help prevent your bloodstream from becoming a toxic dump, says Galland.

4. Become Aware: Breathe
Living on a flat line of high tension does incredible damage to your health, say experts -- metabolism included. Cortisol, the hormone your body produces when you're stressed, increases your appetite and promotes inflammation, reducing the body's sensitivity to metabolic hormones.

To reduce cortisol levels and normalize your metabolism, you must relax, say experts. Mind-body practices such as yoga and tai chi can help reduce stress, but relaxing can also be as simple as slowing down long enough to be conscious of your breath for a few minutes each day. "Breath," says Hyman, "is the doorway to the parasympathetic nervous system," which governs relaxation.