If you’ve ever wondered how to determine your ideal body weight, you’re not alone. It’s no secret that most of us give more than a passing glance to couteured mannequins and half-naked models. 

The concept of ideal body weight (IBW) is shaped, in large part, by social perception of what is both desirable and acceptable. A 2012 Gallup Poll showed that Americans’ self-reported actual and ideal weights steadily increased since Gallup first started collecting the information in 1990.

What’s the significance of the finding? Americans are getting heavier. They are also adjusting their perception of “normal.” And their “ideal weights” are rising alongside their actual weights. 

It’s as if they know they need to lose some weight, but their realization of just how much hasn’t expanded as much as their waistlines have. So they choose an “ideal” that is always within reach of where they are. 

The problem is that nearly 160 million Americans — 75% of men and 60% of women — are overweight or obese. And they are basing their idea of “normal” on what they see, not on what is actually healthy.

If you asked your doctor how to determine your ideal body weight, what do you suppose she would tell you? Do you think it would be a straight-forward, reliable formula? Or do you think she would address the question with a more holistic approach that isn’t so to-the-point?

Interestingly, ideal body weight was originally introduced to estimate dosages for medical use. It had nothing to do with a person’s appearance at a given weight, even though that is what most of us think of. Metabolism of certain drugs is based more on ideal body weight than total body weight, so formulas were derived accordingly.

Four factors affect the most commonly used formulas for ideal body weight:

  1. age
  2. gender
  3. height
  4. body frame size (determined by wrist circumference in relation to height)

Several of the early popular formulas include:

  • Hamwi (1964)
  • Devine (1974)
  • Robinson (1983)
  • Miller (1983)

All formulas for ideal body weight have a format that starts with a base weight. Using the Devine formula, which is the most common, 100 lb is standard for women. A specific increment (5 lb for women) is then added for each inch over 5’, with a 1-10% adjustment for body type and other factors. 

Specifically, the Devine formula is:

  • For men: 50 kg + 2.3 kg/in over 5’
  • For women: 45.5 kg + 2.3 kg/in over 5’

Another metric that is commonly used as a general indicator of healthy weight and potential health risks is body mass index (BMI). The formula for BMI is weight (in kilograms) divided by the square of height (in meters). The World Health Organization recommends a BMI of 18.5-25.

While your BMI may not directly tell you how to determine your ideal body weight, it is the official metric for the classification of different obesity levels. Given that your height is the known variable, you can work backwards to at least determine a weight that will keep you within the recommended BMI range.

By now you may be noticing that something is missing from all these formulas for ideal body weight. None of them take into account body composition (lean weight vs. fat weight). Any of these formulas could classify a bodybuilder or athlete as “overweight.”

Instead of worrying about how to determine your ideal body weight from a formula, shift your focus to health and happiness. Think back to when you felt your healthiest and happiest and were eating well without starving yourself, and make that your goal. 

The concept of ideal body weight is an imperfect one and is not indicative of health. 

Go back to what you think your doctor would say if you asked how to determine your ideal body weight. Hopefully she would assess your need to lose weight, give you a range to start with, then reevaluate on a periodic basis. 

More importantly, she would hopefully remind you that it is more important to make healthy life choices and follow a monitored program of nutrition and exercise. 

Ideal body weight is about so much more than a number on the scale. It has to reflect a doable, sustainable lifestyle with a focus on setting your health up to sustain you for the long haul.