A waist size is considered normal if it is 35 inches or less for women and 40 inches or less for men, according to the National Institutes of Health (NIH). The risk for type 2 diabetes and heart disease increases with greater waist circumferences. The NIH publishes a table of the risks of obesity-associated diseases by body mass index and waist circumference that gives visitors to its website an idea of whether their waist sizes are indicative of any pending health problems.
Waist size should be no more than half of one's height, notes Shape magazine. For example, if a woman stands 70 inches tall, she should have a waist of no greater than 35 inches. If a man stands 80 inches tall, his waist size should be no greater than 40 inches.
Height and weight are used to calculate body mass index (BMI), which is an important factor in determining if a person has a healthy body weight. BMI from 19 to 25 is considered healthy and normal, while anything above or below is generally seen as unhealthy. Shape.com notes that BMI is not a good measure of body fat for elderly adults or adults with a lot of muscle tone, but can be used to judge body fat in other adults.