The waist should be no more than half the length of your height. This measurement was actually found to be more accurate than the body mass index (BMI) used by physicians. Researchers found that those whose waistlines measureed 80 percent of their height lived 16.7 years less than the average lifespan.
A six foot man should have a waistline smaller than 36 inches while a woman who is 5 foot 4 inches should have a waist size no larger than 32 inches for optimal lifespan.
The research was conducted at Oxford Brookes University by Dr. Margaret Ashwell. Ashwell followed people for twenty years to see the effects of her measurements.
http://www.telegraph.co.uk/health/healthnews/10054519/Waist-to-height-ratio-more-accurate-than-BMI.html
