It's as simple as a formula, doctors say.
A report in the New England Journal of Medicine attempts to lay out some guidelines for determining when a person needs to be concerned about their weight. The guidelines are for healthy people - not people who are already sick or have serious medical problems.
Because different people come in different shapes and sizes, the formula determines a person's "body mass index" - both their weight and height combined.
Multiply your weight by the number 703. Now, divide that number by your height in inches squared.
For example, someone who is 5 feet, 5 inches tall and weighs 150 lbs. will have a BMI of 25. According to the guidelines, that number is the highest recommended weight for that person. For this person, a BMI between 19 and 25 is suggested.
You can also determine a healthy weight using a tape measure. Doctors recommend that in general, a woman's waistline shouldn't exceed 35 inches, and a man's waistline shouldn't exceed 40 inches. That's because many of us tend to put on weight around the middle as we age, and that affects our metabolism, putting us at higher risk for problems like diabetes and hypertension. People with a so-called "apple" shape should be particularly careful to monitor an expanding waistline.
The authors of the article emphasize that overweight people should not try to diet down to meet the guidelines. The main goal should be to prevent any further weight gain and aim for losing about 5-10 percent of your weight. Even if you don't feel cosmetically better, you are improving your health significantly.
People should slowly lose weight over a year or two and not diet, but change the way they think about food and how they eat. Exercise is an important factor, too. Walking more during the week is a good start - you don't have to jump into an extreme exercise regimen.
The bottom line for following the guidelines is that while obesity is a serious health problem in the United States, just keeping track of how our body changes as we age makes it possible to control weight before it gets out of control.
For the latest on obesity read "A Weighty Issue".