Dr. Oz says your waist size should be half your height. "For an average size female, that's less than 35 inches; less than 40 inches for a male. Those numbers are obesity thresholds," he says. "Ideally, I'd like you less than 32 and a half inches if you're a woman and less than 35 inches if you're a male."
Dr. Oz says you can measure once a week or once a month. "You can take your choice. I favor once a month because it doesn't change that much from day to day," he says. "But when you're getting in good shape and you're building up muscle, your weight won't drop that much, but your waist size will."