She held her eyes on me a long time. “Do you think I’m fat?” she asked.

       I thought about it, taking too long.

       “No,” I answered.

       “But I’m over 220 pounds. I know people talk about weight. I feel fat. Don’t you think I’m really fat?” “No,” I said again. “I don’t think you’re fat. I think you’re fit.”

       For a long time Americans have been accustomed to think of defining themselves and others as either fat or thin. Approximately 40% of American men and 60% of adult women want to weigh less, and are at this moment considering a new diet to lose that weight. Like many of us, they are obsessed by the weight scale.

       They should not be. Instead, they should be concerned with what they eat, how they move and how they rest.

       Ms. R, who thought herself fat, definitely paid attention to food, activity and rest. Knowing that sleep loss made her tired, cranky and potentially fatter, we had worked successfully on her longstanding insomnia. When I explained the principles of FAR, to eat, move and rest in sequence throughout the day, she applied them. Ms. R ate close to a vegetarian diet, and rarely “pigged out.” She walked after lunch and dinner, and often worked out at the gym, biking on the weekends. She had become strong, able to bench press far more than I weighed.

       Other patients who are equally fit have complained to me that they feel fat. I’ve tried to provide them a few facts:

1. Body Mass Index is not the end-all in determining whether you are fat. The government sets 30 and above as the BMI defining obesity. By this standard Shaquille O’Neal, who often runs a BMI of 33, is clearly fat. So is a large part of the NBA and NFL, including many of the greatest players.
   
   
2. Most of weight is genetically inherited. Though some researchers differ, the general consensus is that 70-80% of one’s weight is determined by genes.
   
   This large genetic factors mean many people will never, never look thin, unless they eat a near starvation diet. Such people certainly exist. In the old days, psychiatric researchers used to call them “thin fat people”, who managed to control their frequently ravenous hunger in order to appear “more attractive.” Many of these folks, especially in the entertainment world, have to utilize extraordinary means to keep their weight down. Some think non-stop about food.
   
   I continue to tell my patients that you cannot control what genes your inherit. You can control what you do with them. Try to follow human design. If you eat, move, and rest, try to eat whole foods, and make sure you work on social support and protecting your rest time, there is a great deal you can do for yourself.
   
   
3. Muscle weighs more than fat. There are now plenty of “overweight” or “obese” triathletes. Born with genes that will never make them look like Jennifer Aniston or Tommy Tune, they are incredibly fit and by medical standards very healthy.
   
   
4. In many cases having a BMI in the “overweight” category of 25-30 is not related to decreased mortality. Having some “extra” weight does not worsen health for many, many people. Waistline is a better predictor of longevity than weight.
   
   
5. Getting fit has huge benefits in preventing heart disease; stroke; Alzheimer’s disease; Parkinson’s disease; and many cancers.
   
   
6. Fit people get depressed less often. Exercise for many is a better way to get out of a depressive episode than medications. As many people weigh more because of medications like anti-depressants, physical activity of many different kinds can improve mood and overall health.
   
   
7. Most epidemiologic studies show that people who exercise 2,500 to 3,000 calories a week have a maximum exercise related increase in their lifespan. Keeping fit makes you feel better and keeps you alive.
   
8. One secret of how “Frenchwomen Don’t Get Fat,” the name of a recent bestseller, is that many Frenchwomen smoke. Many models keep their svelte figure by smoking, or, more extremely, by using cocaine or other stimulants. Fortunately recent trends in societal visions of beauty are moving away from waif-like figures, “heroin chic,” and pencil arms. Many models regard working out as a necessary part of their jobs, and enjoy having well used muscles.

       Ms. R was surprised when I told her I did not think she was fat. After I explained why, she said she felt better. She had not lost weight in years, but her waist size had declined as she exercised. She felt stronger and more able to handle the world. Getting fit made her healthier.

       The same is true of the national population. The question should not be fat or thin. It should be something far more important — fat or fit.

Dr. Matthew Edlund, M.D., M.O.H., director of The Center for Circadian Medicine, is an expert on applied public health, sleep medicine and psychiatry. A former professor at Brown and University of Texas medical schools, he can be reached via email to DocME@DoctorEdlund.com. And CLICK HERE to subscribe to our new Fitcast, via the iTunes Store.