Let's be honest: when we see a severely obese person at the all-you-can-eat buffet, we can't help feeling a twinge of self-righteousness. "Why doesn't that person just stop eating so much? He or she must be putting away a ton of food every day to be so fat."
In reality, what's on that person's plate probably isn't that much different from yours. Adding just 100 extra calories a day -- the equivalent of a small banana or extra slice of bread, or of eliminating your 20-minute morning walk -- will add 10 pounds in only a year. In a decade, you've gained 100 extra pounds.
And once those extra pounds have been packed on, maintaining them doesn't take as much extra fuel as you might guess. The Institute of Medicine has developed a set of equations that predict how much energy a person needs based on his or her weight, height, age, gender and activity. The results are surprising. For example, a 5-feet, 4-inches-tall active woman weighing 93 pounds is obviously underweight, but she needs about 2,100 calories per day to stay at the same weight. So it stands to reason that her same-height, same-age, equally active sister who weighs 204 pounds should need twice as many calories per day to maintain her weight, right?
Not true. According to the Institute's formula, the obese woman needs just 2,800 calories per day to stay at the same weight as her very thin sister. The difference is just 700 calories-a foot long chicken sub sandwich or a plate of nachos -- more than what her sister takes in to maintain less than half the weight.
Losing weight is all about doing the math. Counting calories has been shown over and over to be the most effective way to lose weight and keep it off, but it's very difficult for most people to do so, especially over the long term.
But help may be on the way. Last month, First Lady Michelle Obama launched her "Let's Move" national campaign to end childhood obesity. It's an ambitious effort that includes encouraging kids to exercise, providing healthier meals in schools and giving tax breaks to grocers who move into neighborhoods where healthy food is scarce. Perhaps most important, the Food and Drug Administration and U.S. Department of Agriculture will be creating new ways for consumers to find accurate nutritional information about their food.
That's key because it's a way for all of us to take responsibility for what we put in our mouths. Simply knowing that a 20-ounce cola or 16 ounces of orange juice equals about 250 calories might make a person trying to lose weight think twice before drinking it. And because weight gain and maintenance hinge on such small differences in calorie intake, a small change like skipping your afternoon beverage might, over time, make a big difference in your health. Multiply those small changes by the estimated one-third of Americans who are obese, and suddenly you have a revolution in public health.
Like most revolutions, this one simply needs something to set it off. Let's hope the "Let's Move" initiative provides that spark.