The American Cancer Society states that in addition to quitting smoking, some of
the most important things you can do to help reduce your cancer risk are:
• Get to and stay at a healthy weight throughout life, with a BMI of under 25.
• Be physically active on a regular basis.
• Make healthy food choices with a focus on plant-based foods.
Bodyweight and cancer
One estimate is that one out of every three cancer deaths in the U.S. is linked to
excess body weight, poor nutrition, and/or physical inactivity. These factors are
all related to each other and may all contribute to cancer risk, but of these factors,
bodyweight or more accurately adiposity (fatness) seems to have the strongest evidence
of a causal link to cancer. According to the American Cancer Society, excess
body weight contributes to as many as one out of five of all cancer-related deaths. A
large study involving more than one million participants concluded that the proportion
of all deaths from cancer that is attributable to overweight and obesity in U.S.
adults 50 years of age or older who do not smoke might be as high as 14% in men
and 20% in women.70 A 2017 study by the CDC assessed the incidence of 13 cancers
among more than 630,000 people. The study found that more than 55% of all
cancers diagnosed among women and 24% of cancers among men were associated
with overweight and obesity.
In a dose-response relationship, the risk of cancer increases with increasing body
mass index (BMI) or abdominal fat. People who are overweight have a small increase
in risk, whereas, among the extremely obese, cancer mortality from all sites
is 70% higher than that of people of normal weight. And studies indicate that after
both dietary interventions and bariatric surgery, there are fairly immediate reductions
in cancer incidence following weight loss.
The causal links between body weight and cancer are not well understood. They appear
to vary for different cancers. Excess body fat might affect cancer risk through
effects on immune system function, inflammation, increased levels of hormones,
such as insulin and estrogen, that can stimulate cancer growth, and factors that regulate
Being overweight or obese is clearly associated by epidemiological studies with an
increased risk of the following cancers:
• Breast (in women past menopause)
• Stomach (gastric cardia)
• Colon and rectum
• Endometrium (lining of the uterus)
• Kidney (renal cell)
• Brain (meningioma)
• Multiple myeloma
Being overweight or obese probably raises the risk of other cancers, such as:
• Malignant melanoma
• Non-Hodgkin lymphoma
• Male breast cancer
• Aggressive forms of prostate cancer
The increase in relative risk of cancer varies according to an individual’s weight
classification and specific cancer. Meta-analyses suggest that compared to normal-
weight individuals, the relative risk of getting cancer is 1.2 to 1.5 greater for
overweight and 1.5 to 1.8 greater for obesity. There is a much higher relative risk
for cancer of the esophagus (4.8) and endometrium (7.1) among those of the highest
weight.76 A study of obesity and colon cancer found that overweight women (BMI,
25.0-29.9) had a 37% increase in risk, and obese women, with a BMI of 30 or greater,
had a 93% increase in risk.77 A 2018 study attributes 5.6% of worldwide cancers
to diabetes and suggests that a BMI of above 25 is associated with twice as many
cancers as diabetes.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel