Because of all the ups and downs I've experienced with my weight through the years, I was afraid that dieting might have messed with my metabolism. Now I've learned I don't have anything to worry about. While extremely low-cal diets temporarily lower your metabolism, recent studies suggest that the effects don't last. Researchers in Canada looked at fifty-two overweight women who'd been dieting on and off for an average of eighteen years. They measured the women's resting metabolic rate, then compared those numbers with what their metabolism was expected to be based on their weights, heights, and ages. The result: There was no difference between actual and predicted metabolic rates in all but four dieters. So even if you've lost and regained weight countless times, don't give up. Yo-yo diets don't hurt you; they just don't get you anywhere.