When Scales Lie: Normal Weight but Still at Risk?

People considered average weight may still be "normal weight obese."

ByABC News via logo
January 26, 2010, 11:17 PM

Jan. 27, 2010— -- Monika Sumpter did what many women dream of -- she set a goal to lose weight and dropped 50 pounds.

Despite losing all of that weight, her ratio of fat to muscle was around 25 percent, 5 percent from where she started and dangerously close to what some researchers say is an unhealthy situation.

"I was just shocked. I thought that it was a lot lower, and I thought that I was healthy," Sumpter said.

There are others like Sumpter. As many as 30 million Americans who are considered average weight may actually have what scientists call normal weight obesity, according to a recent study by the Mayo Clinic.

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The study, which followed 6,171 Americans over nine years, found 20 percent to 30 percent of people considered normal weight still have an alarmingly high percentage of body fat.

The Mayo Clinic says that generally, women should have a body fat percentage below 30 percent, while men should have a fat to muscle ratio of less than 20 percent to 25 percent.

Sumpter, a 34-year-old mother of one, is 5 feet 8 inches tall and weighs about 140 pounds, which is in the normal weight range for her height.

However, if 42 of those pounds -- or 30 percent of her weight -- are made up of fat, Sumpter would actually be considered normal weight obese.

That diagnosis means a higher risk of obesity-related diseases, such diabetes, high cholesterol and heart disease, which is the No. 1 killer of women.

"Women with normal weight obesity, meaning those who have high fat and a normal weight have a two times increased risk for death or dying from heart problems or a stroke," said Dr. Francisco Lopez Jimenez, who led the Mayo Clinic study.

Sumpter changed her workout routine, adding more weight-bearing exercises to build lean muscle mass instead of only doing calorie-burning cardio.

"Resistance training is the key," said Sumpter, who is now certified as a personal trainer and works at Equinox in New York. "There are three key components to a healthy lifestyle, which is healthy eating habits, resistance training to build muscle and of course cardio to burn calories and for a healthy heart, but it's a combination of all three."

Today she weighs 20 pounds more than her lowest weight, but her body fat percentage is down to 14 percent.