Body Mass Index

Small vs Large Body Frame

If you have a large body frame, you will naturally need more body mass to support your frame. BMI does not provide a range based on your body frame size.

If you have a large body frame, one way to determine if you are in a healthy BMI range is to shift the ranges by 10% (Source:Wikipedia). Add 10% for a large body frame and deduct 10% for a small body frame. Using this method, if you have a large body frame, you can use the following ranges to determine if you are overweight.

BMI Ranges for People with a Large Body Frame

• BMI below 20.35: you are considered to be underweight.
• BMI from 20.35 to 27.5: you have a normal weight.
• BMI from 27.5 to 33: you are considered overweight.
• BMI from 33 to 38.5: you are moderately obese.
• BMI from 38.5 to 44: you are severely obesity.
• BMI above 44: you are morbidly obese.

How to Figure Out Your Body Frame Size

According to the National Institutes of Health, you can determine your body frame size by measuring your wrist with a tape measure. Use the following chart to see where you fall in terms of body frame size. Women:

• 5 Feet 2 Inches (157.5 cm) or Below
  • Small: wrist size less than 5.5 inches (14 cm)
  • Medium: wrist size 5.5 to 5.75 inches (14 to 14.6 cm)
  • Large: wrist size over 5.75 inches (14.6 cm)
• 5 Feet 2 Inches to 5 Feet 5 Inches (157.5 to 165 cm)
  • Small: wrist size less than 6 inches (15.2 cm)
  • Medium: wrist size 6 to 6.25 inches (15.2 to 15.9 cm)
  • Large: wrist size over 6.2 inches (15.9 cm)
• 5 Feet 5 Inches (165 cm) or Above
  • Small: wrist size less than 6.25 inches (15.9 cm)
  • Medium: wrist size 6.25 to 6.5 inches (15.9 to 16.5 cm)
  • Large: wrist size over 6.5 inches (16.5 cm)

Men:

• 5 Feet 5 Inches (165 cm) or Above
  • Small: wrist size 5.5 to 6.5 inches (14 to 16.5 cm)
  • Medium: wrist size 6.5 to 7.5 inches (16 cm to 19 cm)
  • Large: wrist size over 7.5 inches (19 cm)

Men vs Women

Most men have bigger frames than women, and are more muscular, so for those men, having a higher BMI than a woman of the same height is expected. However the BMI ranges do not differentiate between men and women.

Fat vs Muscle

Athletes tend to have higher muscle mass and weigh more, and sometimes fall under the overweight category. For these people, it does not necessarily mean that they need to lose weight or they are unhealthy. They just have lots of muscle (not fat) that make them weigh more. So they are not the same as someone who is the same weight but has hardly any muscle.

If you are athletic and are falling in the overweight category using BMI, make sure to also use the other methods (body fat percentage, waist-to-height-ratio, waist-to-hip ratio). If they are all within or below the acceptable range, there is probably no health reason for you to lose weight.

On the other hand, if you’ve been exercising and have gained weight, don’t be too quick to assume that all of that is muscle. Some people end up being very hungry and eating more after exercise, especially if they’ve just started to incorporate an exercise routine. You may want to check your body fat percentage to make sure you are not gaining more fat than muscle!

Fat Distribution

BMI does not capture the one very important indicator of potential health risks in the future, which is where the fat is distributed in your body. According to one study, the risk of death of people with normal weight but with high belly/abdominal fat was 2.08 times greater than that of people with normal BMI and waist-to-hip ratio.

So even if you are in the healthy category based on your BMI, if you have a high concentration of fat in your belly area, you are at double the risk of death than people who have a regular belly size.