Is Maximum Weight Limit the New BMI?
You're probably familiar with the term body mass index, or BMI. In a nutshell it's a formula that compares your weight to your height. The exact calculation is: your weight in pounds multiplied by 703, and then divided by your height in inches squared (I know!).
There are tons of calculators online that allow you to plug in your weight and height and do the math for you, but BMI has its flaws. First, "normal" BMI is a range - a result between 19 and 24. For a woman who's 5'6" that can mean a weight anywhere between 120 and 150 pounds.
One professor at the University of Nevada, Reno, thinks that's a problem, so he set out to give people a different calculation he calls the 'maximum weight limit' or MWL. MWL would the single weight in pounds you shouldn't go over. Using software and statistical procedures, he came up with a simpler calculation.
It starts with a baseline.
For men, the baseline is 5'9" tall and a Maximum Weight Limit of 175 pounds
For women, the baseline is 5' tall and a Maximum Weight Limit of 125 pounds
From the baseline you simply calculate how much taller or shorter you are, in inches.
If you're are man, you add or subtract five pounds for every inch.
Women should add or subtract 4.5 pounds for each inch they differ from the baseline height.
Here are a few examples:
5'8" - 175 minus 5 pounds = 170
5'10" - 175 plus 5 pounds = 180 pounds
5'11" - 175 plus 10 pounds = 185 pounds
5'3" - 125 plus 13.5 (4.5 x 3) = 138.5
5'4" - 125 plus 18 (4.5 x 4) = 143
5'5" - 125 plus 22.5 (4.5 x 5) = 147.5
The creator says these Maximum Weight Limits correspond very closely to one point within the normal BMI range: 25.5 for men and 24.5 for women.
While not perfect, I think this is an interesting concept. I'm often asked by my clients, "What's the most I should weight?" The idea of having one number you should strive not to go over can be valuable, but it's difficult to create a one-size-fits-all formula. Frame size and muscle mass have a lot to do with it - I have both male and female clients that are close to if not over these MWLs who have low body fat percentages and are incredibly healthy.
On the flip side I've had many, many clients over the years who are "ideal" in terms of their weight for height, but are extremely unhealthy. A thin person can have a high body fat percentage and not be healthy on the inside. In fact some of the thinnest people I know have the least healthy diets, don't exercise, smoke and are super stressed.
So, bottom line, Maximum Weight Limit has some merit - just don't confuse it as a way of determining if you or someone else is healthy!