Your breast size impacts your BMI, but not necessarily in a manner that should worry you. The Body Mass Index (BMI) is an approximate measure of your body’s fat derived from your body’s total weight and size.
Table of Contents
- 1 Breast Size Impact on the Body Mass Index: Visual Explanations
- 2 When Should I Adjust my BMI Results to my Breast Size?
- 3 What the Science Says About the Breast Size Impact on the BMI
- 4 Do boobs Add to Your BMI?
- 5 Does Breast Size Affect Body Fat Percentage?
- 6 Breast Size Impact on BMI: 1 Simple Conclusion
Every woman is different in their breast weight and in how much fat sits in their breast. The average breast weighs about 1.5 pounds, but this can vary depending on the woman and her age. Understanding your breast’s impact on BMI can help you better understand what it means for your health and fitness goals.
Breast Size Impact on the Body Mass Index: Visual Explanations
BMI is genetically positively correlated with breast size. The larger the breasts, the larger the BMI tends to be.
It means that – more often than not – when people tend to have high BMI compared to the average, those individuals tend to have breast sizes larger than the average:
But it’s not that simple. Height and body mass also need to be factored in.
To illustrate this notion, let’s take two women with identical weights as an example. One is 5’3″ tall with an A-cup bra size, and the other is 5’6″ tall with a D-cup bra size.
The lady with the most significant bra is also taller despite having the same weight as the shorter one. It means that the body fat percentage approximated by her BMI is healthier than the shorter lady exhibiting the same weight who is a bit more “chubby.”
Assuming breast densities are equal (click here for more information about breast density), the woman with a larger bra size carries more fat from her breast than the woman with a smaller bra size.
Consequently – for the same body height and body proportions – the woman with the smallest bra size will have a slightly lower BMI. In the picture below, the lady on the right would have a slightly lower BMI than the one on the left due to less prominent breast size:
When Should I Adjust my BMI Results to my Breast Size?
If you are concerned about whether your breast size may be impacting your BMI, calculate first your BMI on a proven BMI calculator such as BMICalculator.Live.
- If your BMI result falls in the upper end of the healthy BMI range, you are “fine” even if you carry a higher than average amount of fat from your prominent large breast.
- If your BMI result is within a healthy BMI range by only a tiny amount due to your large bra size (ex: your BMI is 20, but you have a D-bras size), you might be slightly underweight: your prominent breast “help you” to land into a healthy BMI range by bringing “more than usual” weight for your size.
In short, knowing exactly how the BMI result needs to be adjusted to your breast size is only a relevant question if your BMI is within the healthy range by a tiny amount. In such a case, the official BMI cut-off may be less relevant and require minor adjustments due to a larger or smaller than average amount of “good fat” sitting in your breast.
What the Science Says About the Breast Size Impact on the BMI
For a deeper understanding of how breast size impacts the BMI, please refer to the scientific resources:
Do boobs Add to Your BMI?
Yes, the Body Mass Index (BMI) is genetically correlated with breast size. Indeed, people with large breasts tend to have higher BMIs in general, as their body mass is also higher for the same height.
Does Breast Size Affect Body Fat Percentage?
Yes, slightly. According to this research paper, the correlation between total breast volume and percent body fat was r =0.40.
Breast Size Impact on BMI: 1 Simple Conclusion
In some case your BMI result needs to be adjusted for context, like Asian people do with the so called Asian BMI. However, knowing exactly how the BMI result needs to be adjusted to your breast size is only a relevant question if your BMI is close to a healthy BMI cut-off.
A few exceptions aside (such as being a professional athlete or a body-builder), a BMI result out of the healthy official cut-off is most likely an indication that you are not as fit as you should regardless of your breast size. Nothing can replace detailed and professional advice from a medical professional. You also may want to talk to your doctor about whether or not you should be wearing bras with smaller cup sizes so that you’re carrying less weight in them. It would not solve excess or lack of body fat, but it could help reduce back pain from having heavy breasts!