You can use one of a number of ways to calculate a healthy size for any given weight, including ideal height calculations, body mass index and waist-for-height measurements. Because none of the methods are perfectly accurate, take them all into consideration, rather than relying simply on one number to determine whether you are at a healthy weight for your height.
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Ideal Body Weight Calculation
To calculate a general ideal body weight -- or IBW -- for women, include 100 pounds for the first 5 feet of height and an additional 5 pounds for each inch over 5 feet. Using this calculation, the ideal body weight for a woman who is 5-foot, 10-inches tall is 150 pounds, which is for a medium frame woman.
To adjust for "big bones" -- a larger frame size -- add an additional 10 percent of the weight, or another 15 pounds, making the IBW for a large-framed, 5-foot, 10-inch woman about 165 pounds.
A limitation of this way of calculating IBW is that it doesn't take body composition into account. It's possible to have too much body fat when you're at an otherwise healthy weight -- a condition called normal weight obesity.
Healthy Body Weight According to BMI
Another method for estimating whether you are at a healthy weight is to use body mass index, or BMI, which involves using your weight in kilograms and dividing it by your height in meters squared -- or your height times your height.
BMI = weight in kilograms / (height in meters x height in meters)
Use an online BMI calculator if you don't want to do the math yourself. A BMI between 18.5 and 24.9 is considered normal, and measurements above this range are considered overweight. According to calculations, a weight between 129 and 174 pounds is within this healthy BMI range for a woman who is 5-foot, 10-inches tall.
BMI works well for many people. However, a problem with BMI is that it can overestimate body fat in athletes and other people who have a lot of muscle and underestimate body fat in elderly individuals, since it doesn't actually measure body fat. A study published in The American Journal of Clinical Nutrition in 2012 found that a wide range of percentages of body fat are associated with a given BMI. For example, a woman with a BMI of 18.5 might have a body fat percentage of anywhere from 24.6 to 32.3 percent. A healthy body fat range for women is between 20 and 32 percent, so someone could have a relatively low BMI of 18.5 and still have a body fat percentage at the high end of what is healthy.
Take Waist Circumference Into Account
No matter what your weight or your BMI, it isn't healthy to have a large waist. In women, a waist circumference of more than 35 inches is associated with an increased risk of heart disease and other health problems, such as high cholesterol and type 2 diabetes.
Your waist-to-height ratio can help you determine whether you have a healthy waist size for your height. Your waist measurement divided by your height measurement should be between 0.42 and 0.48, with any measurement higher than that indicating you're overweight. For a woman who's 5-foot, 10-inches tall -- or 70 inches tall -- a waist circumference of between 30 and 34 is healthy. An easy way to remember it is that your waist measurement should be no more than half of your height in inches.
Getting Closer to a Healthy Weight
Should you find that your weight, BMI or waist circumference is outside the healthy range, take a few relatively simple steps to help improve your body composition and decrease any risk to your health. Steps include following a balanced, reduced-calorie diet including a mix of lean protein, whole grains and fiber-rich fruits and vegetables and watching your portion sizes. Increase your weekly aerobic activity to at least 300 minutes, and participate in at least two strength-training workouts per week to build muscle and help limit muscle loss while you lose weight. Muscle burns more calories than fat even when you're at rest, so you don't want to lose your metabolism-boosting muscle, just the fat.