Simply put, a healthy weight means you have the right amount of body fat in relation to your overall body mass. It’s a weight that allows you to feel energetic, reduces health risks, helps prevent premature aging (such as worn-out joints from carrying around too much weight) and improves your quality of life.
Stepping on the scale only tells you your total weight — including bone, muscle and fluid — not how much of your weight is fat. The scale also doesn’t tell you where you’re carrying that fat. In determining health risks, both of these factors are more important than is weight alone.
So how do you know if you’re at a healthy weight? While there are no objective standards for what weight “looks good,” there are standards for what determines a healthy weight.
The most accurate way to determine how much fat you’re carrying is to have a body fat analysis. This requires a professional using a reliable method of estimation, such as weighing a person underwater or using an X-ray procedure called dual energy X-ray absorptiometry. Either method can be expensive and fairly complicated. A procedure called bioelectric impedance analysis is more widely available, but its accuracy can vary.
The most common method to determine weight-related health risk is the
National Institutes of Health threefold approach:
Your body mass index (BMI) The circumference of your waist Personal medical history
Body mass index (BMI)
BMI is a tool for indicating your weight status (see the table here). The mathematical calculation takes into account both your weight and height.
Although BMI doesn’t distinguish between fat and muscle, it more closely reflects measures of body fat than does total body weight.
Although a BMI number tends to correlate with body fat for most people, it’s not always a good match. Some people may have a high BMI but relatively little body fat. For example, an athlete may be 6 feet 3 inches tall and weigh 230 pounds, giving him a BMI of 29 — well above the classification of healthy weight. But he’s not overweight because training has turned most of his weight into lean muscle mass.
By the same token, there may be some people who have a BMI in the “healthy”
range but who carry a high percentage of body fat. For most people, though, BMI provides a fairly accurate approximation of health risk as it relates to their weight.
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WHAT'S YOUR BMI?
To determine your BMI, find your height in the left column. Follow that row across to the weight nearest yours. Look at the top of that column for your approximate BMI. Or use this formula:
Multiply your height (in inches) by your height (in inches).
Divide your weight (in pounds) by the results of the first step.
Multiply that answer by 703. (For example, a 270-pound person, 68 inches tall, has a BMI of 41.
Source: National Institutes of Health, 1998
*Asians with a BMI of 23 or higher may have an increased risk of health problems
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Waist measurement
Many conditions associated with excess weight, such as high blood pressure, abnormal levels of blood fats, coronary artery disease, stroke, diabetes and certain types of cancer, are influenced by the location of body fat.
Fat distribution can be described as apple-shaped or pear-shaped. If you carry most of your fat around your waist or upper body, you’re referred to as apple-shaped. If most of your fat is around your hips and thighs or lower body, you’re pear-shaped.
In general, when it comes to your health, it’s better to have a pear shape than an apple shape. If you have an apple shape, you carry fat in and around your abdominal organs. Fat in and around your abdomen increases your risk of developing disease. If you have a pear shape, your risks aren’t as high.
To determine whether you’re carrying too much weight around your middle, measure your waist. Find the highest point on each hipbone and measure around your body just above those points. A measurement exceeding 40 inches in men or 35 inches in women indicates an apple shape and increased health risks.
The table on the next page can help you determine whether to be concerned about your waistline.
Although these cutoffs of 40 and 35 inches are useful guides, there’s nothing magic about them. It’s enough to know that the bigger the waistline, the greater your health risks.
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IS YOUR HEALTH AT RISK?
If your BMI is less than 18.5, talk with your doctor. You may be at risk of health conditions associated with a low body weight. A BMI of 18.5 to 24.9 is considered a healthy range, but Asians with a BMI of 23 or more may have an increased risk of health problems. If your BMI is higher, see below.
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Medical history
Your BMI and waist measurement numbers don’t give you the full picture of your weight status. A complete evaluation of your medical history also is important. In talking with your doctor about your weight, consider:
Do you have a family history of obesity, cardiovascular disease, diabetes, high blood pressure or sleep apnea? This may mean increased risk for you.
Have you gained considerable weight since high school? Even people with normal BMIs may be at increased risk of weight-related conditions if they’ve gained more than 10 pounds since young adulthood.
Do you have a health condition, such as high blood pressure or type 2 diabetes, that would improve if you lost weight
Do you smoke cigarettes or engage in little physical activity? These factors can compound the risk represented by excess weight.
BMI and waist measurement are snapshots of your current weight. The medical history helps reveal your risk of being overweight or of developing weight-related diseases.
So what’s your healthy weight?
If your BMI shows that you’re not overweight, if you’re not carrying too much weight around your abdomen, and if you answered no to all of the medical history questions, there’s probably little health advantage to changing your weight. (But you may still improve your health through a healthy diet and physical activity.)
If your BMI is between 25 and 30 or your waist measurement exceeds healthy guidelines, and you answered yes to one or more of the medical history questions, you’ll probably benefit from losing a few pounds.
Talk to your doctor before you start to lose weight. And if your BMI is 30 or more, you’re considered obese. Losing weight should improve your health and reduce your risk of weight-related illnesses.
Now if your analysis shows that you’re at a healthy weight, but you’re still dissatisfied with the way you look, then you’ve got some thinking to do. If you’re at the middle or upper end of a healthy BMI, there’s probably little risk to losing a few pounds. But if you’re at the lower end of a healthy BMI range, and losing weight would push you into the underweight category (less than 18.5), then losing weight may put your health at risk.