You have probably known about the Body Mass Index (BMI) as a way to evaluate health risk for cardiovascular disease and diabetes. BMI is the ratio between your height and your weight.

What’s a healthy BMI?

Here the numeric health numbers for BMI from the National Institutes of Health (NIH):

BMI Category	BMI Range
Underweight	Below 18.5
Healthy	18.5 – 24.9
Overweight	25.0 – 29.9
Obesity	30.0 or above

Do you know your own BMI? If not, NIH provides a simple online calculator to find your BMI.

Is BMI linked with aggressive prostate cancer?

A link between high BMI and the risk of being diagnosed with prostate cancer (PCa) has long been explored. For example, a 2005 journal article found “a higher BMI was positively associated with being diagnosed with prostate cancer.”^[i] The same article also reported an association between high BMI and the greater likelihood of having more aggressive PCa.

Ironically, obesity itself has been linked with lower PSA, even in men with more aggressive PCa. This may be due to increased blood volume in obese men.^[ii] Even so, De Nunzio, et al. (2011) reported that “… obesity is associated with an increased risk of a high-grade Gleason score when prostate cancer is diagnosed at biopsy.”^[iii]

A 2021 study of PCa patients found that men in their study population who had a normal BMI had low Gleason scores, while “…there was a significant association between high Gleason score and high BMI.”^[iv] The authors summarize current theories as to why this might occur:

High BMI provides a favorable biological microenvironment for tumor onset and growth through some proposed mechanisms which involve alterations in the endocrine system, notably, the levels of testosterone, estrogen, and insulin-like growth factor-I.

They also acknowledge that not all studies find a link between BMI and aggressive PCa.

A better predictor than BMI?

There is general scientific concern about the connection between obesity and cancer risk in general. However, the problem may not be the amount of fat in a person’s body but rather where the fat is located. There is much more danger of chronic and even life-threatening disease among individuals with belly fat. These are “apple shaped” people as opposed to “pear shaped” people. BMI alone does not take fat location into account. If BMI is not the best weight-related predictor of aggressive PCa, is there a better one? Probably not yet—but there seems to be a promising metric for predicting colon cancer that goes further than just BMI.

In September 2025, a group of researchers proposed an integrated system called A Body Shape Index (ABSI). This takes into account how body fat is distributed by integrating height, weight, and waist circumference (WC).^[v] Note the addition of how big around the waist is, a number that indicates fat concentrated around the central organs. In other words, the APSI blends BMI with how big the waist measures.

The authors of the ABSI journal article analyzed all previously published cancer studies that factored in BMI+WC. They concluded that when BMI+WC were blended into A Body Shape Index, it “demonstrates remarkable specificity for specific cancer types in cancer risk predictions.” It was especially predictive of colon cancer among “high-risk male populations” with belly fat.

However, this did not prove true for PCa. As they wrote, “Available evidence does not support the routine application of ABSI for predicting prostate or breast cancer risks.”

Thus, for the time being, you can’t use body numbers like weight, height, and waist circumference to determine if you’re at risk for PCa. Whether or not you have known risk factors (e.g., family history of prostate/breast cancer, exposure to toxic substances, ethnicity, etc.) the best thing you can do to keep your risk as low as possible is to eat a healthy diet, exercise, maintain healthy weight, have loving relationships, and manage stress. In fact, simply do all of these things to increase your odds of having a long, healthy, and happy life.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

References

[i] Freedland SJ, Terris MK, Platz EA, Presti JC Jr. Body mass index as a predictor of prostate cancer: development versus detection on biopsy. Urology. 2005 Jul;66(1):108-13.
[ii] Gioia A, Manco R, Tenaglia RL, Tirabassi G, Balercia G. Relationship between BMI, PSA and histopathological tumor grade in a Caucasian population affected by prostate cancer. Global J Med Clin Case Reports 1 (2): 037-042.
[iii] De Nunzio C, Freedland SJ, Miano L, Finazzi Agrò E et al. The uncertain relationship between obesity and prostate cancer: an Italian biopsy cohort analysis. Eur J Surg Oncol. 2011 Dec;37(12):1025-9. 
[iv] Nwadi UV, Nwofor AME, Oranusi CK, Orakwe JC et al. Correlation between Body Mass Index and Gleason Score in Men with Prostate Cancer in Southeastern Nigeria. Niger J Surg. 2021 Jan-Jun;27(1):22-27.
[v] Liu H, Fu H, Wang Z, Yao Z et al. The predictive value of a body shape index as a novel obesity metric for cancer risk: a systematic review and meta-analysis. Front Nutr. 2025 Sep 24;12:1667466.