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Body mass index (BMI) and the right weight for my height?

(1) Alice,

A friend and I were discussing this. We both try to stay healthy by eating well (high fiber, low fat, lots of veggies, fruit, etc.) and living an active enough lifestyle (hiking, rock climbing, biking, etc.) that we stay in shape. The question we have, then, is what the current "rules" are for appropriate weight/height ratios? Or are such measurements now thrown out in favor of body fat percentage measurements? She's 5'1" and I'm 6'1" and we're curious what the medical rule of thumb would be for how much each of us "should" weigh...mostly because we're wondering if it takes into account things like muscle mass. What would the current medical/health industry recommend each of us weigh? Are these numbers accepted or are they seen as not as important as they might have been 20 years ago. If you have actual numbers, we'd be curious to see that too. Thanks! I have a dinner riding on this!

— Curious

(2) Dear Alice,

Could you clarify the Body Mass Index deal? According to one BMI chart, I am "slightly overweight" because I am 5' 5-1/2" tall and weigh 160 lb. I am also very muscular and have a large frame. The lower BMI readings are labeled "ideal," but I've heard muscle weighs more than fat, so if the chart does not include the muscle factor, is it basically saying that it's "ideal" NOT to have extra muscle? I look slender and have never been told by a doctor to lose weight. I'm a twenty-four-year-old female, lacto-ovo-vegetarian, and get lots of exercise, including walking and frequent "sweaty" workouts.

— Scales

Dear Curious and Scales, 

If you're trying to find your "ideal" weight, you may not want to bet your bottom dollar on a height-weight ratio, or any one indicator for that matter. There are a number of factors that impact a person’s weight, making it difficult to determine someone’s ideal numbers. Additionally, the American Medical Association has indicated that body mass index (BMI) isn't to be used for diagnostic purposes any longer. When trying to assess a person's body composition, there are other tools that health care providers can use. However, no matter where the scale points, maintaining good nutrition and regular physical activity are two signs that you're making choices that support your health and well-being. 

One historically popular way to compare height and weight is BMI. This measure uses a math equation to create a ratio, similar to the older height-weight charts. However, many professional associations have stated that using BMI to assess individuals isn't necessarily predictive of their health or body fat. This is because it fails to acknowledge differences in body composition, and other tools may be more effective in doing so. Additionally, BMI has a racist and harmful history in order to exclude certain groups from accessing care or insurance. While BMI may be used by some health care providers, it excludes factors like genetics and body composition and therefore doesn't give a full picture of a person's body. All of this said, government organizations such as the Centers for Disease Control and Prevention and the National Institutes of Health still use BMI in their recommendations, despite its flaws. 

Other tools can be used to get a better understanding of a person's body composition. Some of these include measuring the different types of fat in the body, measuring waist circumference, and examining genetic factors. While some of these tools can only be used with the support of a health care provider, measuring waist circumference can be as simple as pulling out a tape measure. As it turns out, carrying more weight around the belly (as opposed to the hips) carries more health risks than fat in other areas of the body. According to the National Institutes of Health (NIH), the chances of developing heart disease, hypertension, and type 2 diabetes increases when waist circumference exceeds 35 inches for non-pregnant folks who are assigned female at birth or 40 inches for people assigned male at birth. 

Measurements aside, yet another way to define "healthy" weight is by whatever size your body settles at naturally when you follow a balanced diet and get the recommended amounts of physical activity. This is called set-point theory and is the idea that your body tries to maintain that settled weight. Additionally, you may want to think about whether or not your nutrition and activity support your body's needs. Can you do the things you want to do? You may also think about how you feel in your body. That may be more helpful to you than the measurements from the typical assessment tools used in a health care setting. 

If you’re interested in exploring these topics further, talking with a registered dietitian might also help; they can assess your eating patterns, activity levels, and body size to help determine what weight best supports the health and needs of your body. People come in many shapes and sizes and as such, "ideal" weight can vary from person to person. 

Hopefully this information helps to settle the score! 

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Last updated Dec 29, 2023
Originally published Nov 01, 1993