Is There a "Perfect" Weight?

The concept of an "ideal body weight" (IBW) was originally developed by insurance companies in the early 20th century to estimate life expectancy and set premiums. Today, it serves as a clinical baseline for medical professionals, particularly for determining drug dosages. However, modern medicine acknowledges that health comes in many shapes and sizes, and a single "ideal" number is an oversimplification. It is better to aim for a healthy weight range.

The Major IBW Formulas

Over the decades, scientists have developed several formulas to calculate IBW. They are generally based on a baseline weight for a height of 5 feet, plus a specific amount of weight for every inch over 5 feet.

1. The Devine Formula (1974)

The Devine formula is the most widely used formula in clinical settings, particularly by pharmacists for calculating doses of medications like antibiotics that clear through the kidneys.

• Men: 50.0 kg + 2.3 kg per inch over 5 feet
• Women: 45.5 kg + 2.3 kg per inch over 5 feet

2. The Hamwi Formula (1964)

Originally designed as a quick rule-of-thumb for physicians, this formula is still popular in the US.

• Men: 48.0 kg (106 lbs) + 2.7 kg (6 lbs) per inch over 5 feet
• Women: 45.5 kg (100 lbs) + 2.2 kg (5 lbs) per inch over 5 feet

3. The Robinson (1983) and Miller (1983) Formulas

These were introduced as modifications to Devine and Hamwi to account for the fact that previous formulas tended to underestimate IBW in taller individuals and overestimate it in shorter individuals.

BMI-Based Ideal Weight

Instead of a single number, using the Body Mass Index (BMI) provides a range of ideal weights. A "normal" BMI is considered to be between 18.5 and 24.9. To find your healthy weight range, you can reverse-engineer the BMI formula:

• Minimum Healthy Weight: 18.5 × [height (m)]^2
• Maximum Healthy Weight: 24.9 × [height (m)]^2

For someone who is 5'9" (1.75m), their healthy BMI weight range is roughly 125 lbs to 168 lbs (56.6 kg to 76.2 kg).

Healthy Weight Ranges by Height (General Guide)

Here is a quick look at the approximate healthy weight ranges for adults based on the BMI 18.5-24.9 criteria:

• 5'0" (1.52m): 97 - 127 lbs
• 5'4" (1.63m): 110 - 145 lbs
• 5'8" (1.73m): 125 - 164 lbs
• 6'0" (1.83m): 140 - 183 lbs

When IBW and BMI Don't Apply

It is crucial to remember that these formulas do not account for:

• Muscle Mass: Athletes and bodybuilders will often weigh significantly more than their "ideal" weight due to dense muscle tissue, yet they are perfectly healthy.
• Frame Size: Some people have naturally wider shoulders, larger bones, or broader hips. The formulas assume an "average" frame.
• Age: As we age, a slightly higher weight (BMI 25-27) is sometimes associated with better outcomes and protection against frailty.

Our Ideal Weight Calculator utilizes all major clinical formulas (Devine, Hamwi, Robinson) and the BMI range to provide you with a comprehensive overview of your healthy target weight based on your gender and height. Always consult with a healthcare provider before setting strict weight loss goals.