George Fernandez, a professor of applied statistics and director of the Center for Research Design and Analysis at Nevada, says that the "range" approach in BMI calculation does not stick in individuals' minds.
"We need a "Maximum Weight Limit, or MWL, one number that we know we can't go over, just like a speed limit," he said.
Thus, he used SAS software and statistical procedures to discover a much simpler way of calculating a Maximum Weight Limit, which closely corresponds to weight recommendations listed on BMI charts.
And a person does not need to calculate or know his or her BMI, nor do they need a chart or online calculator to figure out your Maximum Weight Limit.
"It's a very simple calculation that most of us can do in our heads," he explained.
For men and women, there is a baseline height and weight. For men, the baseline is 5-feet, 9-inches tall and a Maximum Weight Limit of 175 pounds, meaning that a 5-foot, 9-inch tall man should weigh no more than 175 pounds.
For women, the baseline is 5-feet tall and a Maximum Weight Limit of 125 pounds.
"These are nice round numbers that people can easily remember: 5-feet, 9-inches tall, 175 pounds for man; and 5-feet tall, 125 pounds for a woman," explained Fernandez.
From that starting point, one can simply calculate how much taller or shorter he or she is, in inches.
If a man, he needs to add or subtract 5 pounds for every inch he is taller or shorter than 5 feet, 9 inches. So, if he is 5-feet, 11-inches tall, he is 2 inches taller than the baseline of 5 feet, 9 inches. He should add 5 pounds for each of those 2 inches, 10 pounds, to the baseline Maximum Weight Limit of 175. Thus, his Maximum Weight Limit is 185 (175 pounds plus 10 pounds).
Women add or subtract 4.5 pounds for each inch they differ from the baseline height of 5-feet tall.
These Maximum Weight Limits correspond very closely to BMIs of 25.5 for men and 24.5 for women. A BMI of 18.5 to 25 BMI is diagnosed as the "healthy range."
Fernandez used a slightly lower BMI base for women and a slightly higher one for men because, on average, women have less muscle mass than men.
"Now people can calculate their own Maximum Weight Limit, based on the BMI index, but without any calculators or charts. And, all they have to remember is that one number, 185 pounds for example, which is easier for most people than retaining a weight range, such as 155 to 185 pounds," said Fernandez.
He also noted that this simple formula could be very useful in medically underserved areas of the world, and for individuals without access to technology and charts.
"Anyone, anywhere can calculate their Maximum Weight Limit if they know their height and this simple formula. People can calculate this in their heads and remember this," he said.
Fernandez will present his Maximum Weight Limit calculation at the Nevada Public Health Association Conference at the University of Nevada.