Can You Be Really Thin and Still Be in Good Health?

Answers to your questions about the news.
Jan. 9 2007 6:09 PM

Are Skinny Girls Unhealthy?

What if they're like that naturally?

Download the MP3 audio version of this story here, or sign up for The Explainer's free daily podcast on iTunes.

Later this week, the Council of Fashion Designers of America will issue guidelines for runway shows that encourage a healthier lifestyle for models. In New York, catwalkers won't be tested for a minimum body mass index, as they are in Madrid and Milan. Is it possible to have a very low BMI and still be healthy?

Torie Bosch Torie Bosch

Torie Bosch is the editor of Future Tense, a project of Slate, the New America Foundation, and Arizona State that looks at the implications of new technologies. 

Only if it's completely natural—and that's rare. Many people are predisposed to be thin, but if a model has a BMI of below 18—the threshold used in Madrid—she is almost certainly practicing unhealthy habits, such as restricting food intake or overexercising. Someone who's 5-foot-11, like most female models, would have to weigh less than 130 pounds to fall short of the threshold. To get to that point, even a natural waif would likely have to skip meals, exercise too much, or use diet aids.

People who engage in these activities can face a myriad of health problems, often because of their low body-fat levels. BMI doesn't measure body fat directly; it looks only at the ratio of a person's height and weight. Doctors say direct fat measurements—via skinfold calipers, for example—tell you more about someone's health. (BMI is popular because it's so easy to calculate.) Women with less than 12 percent body fat can be at risk for serious health problems or starvation.

Human bodies have evolved to be able to withstand starvation on occasion. In the absence of sufficient caloric intake, the body's metabolism slows down, and the liver, heart, and other organs may reduce their tissue reserves. For instance, the heart keeps backup capacity so that we can run very fast when we need to get away from a bad situation. The heart of someone who is starving, however, may not be able to hold extra muscle mass stockpiled for that sort of occasion.

Because of these adapting body changes, people who are too thin can function normally much of the time. But a major blow to the system, like a bad bout of influenza or gastroenteritis, could throw off the tenuous balance and lead to cardiovascular problems and fainting. Other long-term potential complications of being too thin could include a diminished ability for the bowels to absorb nutrients, lost menstrual cycle, and decreased thyroid function.

The standards set by Milan fashion-industry heavyweights require models to obtain a license issued by a panel of experts before being allowed to walk the runway. This panel is supposed to take models' ethnic and geographical background into consideration before issuing or denying someone a permit. Some research suggests that Asians, as well as members of some Australian Aboriginal tribes, may have a naturally lower BMI than Caucasians. However, the details on this are still unclear.

Got a question about today's news? Ask the Explainer.

Explainer thanks Ovidio Bermudez of the National Eating Disorder Association, Bill Dietz of the Centers for Disease Control and Prevention, Boyd Swinburn of Deakin University, and Terri Wheeldon of the Mayo Clinic.

TODAY IN SLATE

Frame Game

Hard Knocks

I was hit by a teacher in an East Texas public school. It taught me nothing.

Chief Justice John Roberts Says $1,000 Can’t Buy Influence in Congress. Looks Like He’s Wrong.

After This Merger, One Company Could Control One-Third of the Planet's Beer Sales

Hidden Messages in Corporate Logos

If You’re Outraged by the NFL, Follow This Satirical Blowhard on Twitter

Sports Nut

Giving Up on Goodell

How the NFL lost the trust of its most loyal reporters.

How Can We Investigate Potential Dangers of Fracking Without Being Alarmist?

My Year as an Abortion Doula       

  News & Politics
Weigel
Sept. 16 2014 11:41 AM Klobucharmania: Catch It!
  Business
Business Insider
Sept. 16 2014 10:17 AM How Jack Ma Founded Alibaba
  Life
Atlas Obscura
Sept. 16 2014 8:00 AM The Wall Street Bombing: Low-Tech Terrorism in Prohibition-era New York
  Double X
The XX Factor
Sept. 15 2014 3:31 PM My Year As an Abortion Doula
  Slate Plus
Tv Club
Sept. 15 2014 11:38 AM The Slate Doctor Who Podcast: Episode 4  A spoiler-filled discussion of "Listen."
  Arts
Brow Beat
Sept. 16 2014 11:40 AM How to Put Things in Your Fridge
  Technology
Future Tense
Sept. 16 2014 7:36 AM The Inspiration Drought Why our science fiction needs new dreams.
  Health & Science
Bad Astronomy
Sept. 16 2014 7:30 AM A Galaxy of Tatooines
  Sports
Sports Nut
Sept. 15 2014 9:05 PM Giving Up on Goodell How the NFL lost the trust of its most loyal reporters.