Category: Metabolism

The two primary hormones that control appetite are ghrelin and leptin. They serve as biological on/off switches. Ghrelin is mainly produced in the lining of the stomach and switches on appetite. Leptin is secreted by fat cells and turns off appetite by signaling when you’re full.

Yet another reason not to let your weight seesaw: You'll hamstring your metabolism. "My patients with the lowest metabolisms are the weight cyclers," says Scott Isaacs, MD, clinical instructor of medicine at the Emory University School of Medicine. "When you lose weight, you lose muscle and fat, but when you gain it back, it's mostly fat, which burns fewer calories."

Estrogen helps insulin metabolize blood sugar. So when your levels of the hormone naturally begin to drop as you head toward menopause, this estrogen deficiency increases your insulin resistance, "a condition that causes your body to store the food you eat as fat instead of burning it as energy," Dr. Isaacs explains.

Can't sleep? Having memory lapses? Your hormones may be to blame. They can wreak havoc on how you feel, think and function at different times in your menstrual cycle. Luckily, these changes are predictable. By anticipating your hormonal ebbs and flows, you can head off ailments such as cramps and headaches.

"Any time you lose weight, you see improvements in glucose metabolism," says Scott Isaacs, M.D., author of "Hormonal Balance" and a clinical instructor of medicine at Emory School of Medicine. "And anytime you restrict calories, you get weight loss. But if you do something unsustaniable you get fatigue after a while and ultimately gain the weight back." "During a fast, a person can go into starvation ketosis, which reduces appetite. They won't be hungry because of the ketones -- a byproduct of fat -- that masks hunger. But as soon as they do something where they are no longer ketotic, there's a rebound appetite, which can be hard to control," Isaacs says.