How Much Should I Weigh?

At some point, most people have attempted to lose weight or know someone who has. This is often due to societal perceptions of an “ideal” body weight, influenced by media, social platforms, and entertainment industries. However, the concept of Ideal Body Weight (IBW) was originally developed for medical purposes, particularly for determining drug dosages, rather than aesthetic appeal. Research has shown that certain medications are better dosed based on IBW rather than total body weight. IBW is also widely used in sports, where weight classifications play a significant role.

That said, IBW is not a flawless measure of health. It does not account for muscle mass versus body fat percentage, meaning that highly athletic individuals may be classified as overweight despite being in excellent physical condition. For this reason, IBW should be seen as a reference point rather than a definitive indicator of health or a target weight to achieve. Being above or below your IBW does not necessarily mean you are unhealthy.

Factors That Influence Ideal Weight

There is no single formula that can accurately determine the “perfect” weight for an individual. Metrics like IBW and Body Mass Index (BMI) provide general guidelines, but overall health is more dependent on lifestyle choices—such as balanced nutrition, regular exercise, and sufficient sleep—than on achieving a specific number on the scale. Various factors can influence a person’s ideal weight, including:

Age

After puberty, height stabilizes—typically around ages 14-15 for girls and 16-17 for boys. Over time, natural aging leads to a gradual decrease in lean muscle mass and an increased tendency to store fat. By age 70, men and women may lose 1.5 and 2 inches in height, respectively. While these changes are inevitable, maintaining a healthy diet, managing stress, and staying active can help slow the process.

Gender

On average, men weigh more than women of the same height due to higher muscle mass and greater bone density. Conversely, women tend to have a higher body fat percentage, contributing to natural weight differences.

Height

Taller individuals generally weigh more because they have greater muscle mass and body fat. A man of the same height as a woman will typically weigh 10-20% more.

Body Frame Size

A person’s skeletal structure, or body frame size, can significantly impact their ideal weight. Frame size is typically classified as small, medium, or large based on wrist circumference relative to height.

For Women

• Under 5’2″:
  • Small frame: Wrist < 5.5″
  • Medium frame: Wrist 5.5″–5.75″
  • Large frame: Wrist > 5.75″
• 5’2″ to 5’5″:
  • Small frame: Wrist < 6″
  • Medium frame: Wrist 6″–6.25″
  • Large frame: Wrist > 6.25″
• Over 5’5″:
  • Small frame: Wrist < 6.25″
  • Medium frame: Wrist 6.25″–6.5″
  • Large frame: Wrist > 6.5″

For Men

• Over 5’5″:
  • Small frame: Wrist 5.5″–6.5″
  • Medium frame: Wrist 6.5″–7.5″
  • Large frame: Wrist > 7.5″

Larger-framed individuals naturally weigh more than smaller-framed individuals of the same height, impacting both IBW and BMI calculations.

IBW Formulas for Estimating Ideal Weight

IBW formulas were originally created to determine appropriate medication dosages. These formulas base IBW on a standard weight at 5 feet of height, with additional weight increments per inch above that.

Common IBW Formulas

• Hamwi Formula (1964)
  • Male: 48.0 kg + 2.7 kg per inch over 5 feet
  • Female: 45.5 kg + 2.2 kg per inch over 5 feet
• Devine Formula (1974)(Most commonly used IBW formula today)
  • Male: 50.0 kg + 2.3 kg per inch over 5 feet
  • Female: 45.5 kg + 2.3 kg per inch over 5 feet
• Robinson Formula (1983)(Modification of Devine)
  • Male: 52 kg + 1.9 kg per inch over 5 feet
  • Female: 49 kg + 1.7 kg per inch over 5 feet
• Miller Formula (1983)(Modification of Devine)
  • Male: 56.2 kg + 1.41 kg per inch over 5 feet
  • Female: 53.1 kg + 1.36 kg per inch over 5 feet

For example, using the Devine Formula, a 5’10” male would add (2.3 × 10) kg to 50 kg, resulting in an IBW of 73 kg (161 lbs).

BMI and Healthy Weight Ranges

The World Health Organization (WHO) defines a healthy BMI range of 18.5 to 25 for both men and women. BMI is widely used in the medical field to assess potential health risks. A higher BMI is often associated with increased risks of conditions such as obesity, heart disease, and diabetes.

BMI for Children and Teens

For individuals under 18, BMI is assessed differently. The Centers for Disease Control and Prevention (CDC) recommends maintaining a BMI between the 5th and 85th percentile for a given age. Growth charts specific to children and teens provide a better reference for healthy weight ranges.

Limitations of IBW and BMI Calculators

No single formula can determine a universally “correct” weight. IBW and BMI calculations:

• Do not account for muscle mass or body fat percentage.
• May not apply to individuals with extreme body compositions (e.g., bodybuilders, those with physical disabilities).
• Are best used as general guidelines rather than strict targets.

Conclusion

Rather than fixating on a specific weight, focus on overall health—regular exercise, balanced nutrition, proper sleep, and stress management. Weight is just one factor in well-being, and true health extends beyond a number on the scale.