Most people know that smoking dramatically raises cancer risk. But far fewer know that obesity — a condition affecting more than 40% of American adults — is also a major, well-documented cancer risk factor. At Missouri Metabolic Health, we treat the full spectrum of metabolic conditions, including obesity, prediabetes, metabolic syndrome, PCOS, and type 2 diabetes. And understanding the link between excess body weight and cancer is a core part of why we take metabolic health so seriously.
In this post, we're breaking down the science: which cancers are linked to obesity, why the connection exists, who faces the highest risk, and what proactive steps you can take right now.
Is Obesity "the New Smoking" When It Comes to Cancer?
You may have heard this phrase — and while it's a useful way to raise awareness, the comparison needs some nuance.
Smoking remains the single most significant modifiable risk factor for cancer. It accounts for approximately 19% of cancers and 28% of cancer-related deaths in the United States. Obesity, by comparison, is responsible for roughly 7–8% of both cancers and cancer-related deaths in the U.S.
So no, obesity is not the new smoking — but that doesn't mean the risk is small. Seven to eight percent of all U.S. cancers is an enormous public health burden, and it's one that is largely preventable. Two of the most impactful things any adult can do for their long-term health are:
- Never smoke — or get help to quit now
- Achieve and maintain a healthy weight
Both of these are goals your primary care physician and/or an obesity medicine specialist can actively help you work toward. There is more hope and more treatment available than ever before — so please don't hesitate to ask for help.
The 13 Cancers Linked to Obesity
Research has identified at least 13 distinct cancers with a well-documented association to obesity. Here's an overview of each, along with what you should know about screening:
1. Endometrial (Uterine) Cancer
This has the strongest association with obesity of any cancer on this list. Women with a BMI of 40 or greater face seven times the risk of endometrial cancer compared to women with a BMI of 25 or less. The primary driver is excess estrogen, which is produced by adipose (fat) tissue and is a known trigger for endometrial cell changes.
2. Liver Cancer
Individuals living with obesity are approximately twice as likely to develop liver cancer. There is currently no routine screening guideline for liver cancer in obesity alone — but if you have metabolic dysfunction-associated steatotic liver disease (commonly called fatty liver disease) or a history of hepatitis B or C, you should be receiving periodic liver ultrasounds. All adults should be screened at least once for hepatitis B and C, regardless of perceived risk.
3. Postmenopausal Breast Cancer
All women should begin breast cancer screening (mammography) around age 40, with most guidelines recommending annual screenings continuing through age 74. If you have a family history of breast cancer or other elevated risk factors, earlier or more frequent screening may be recommended. Talk to your primary care doctor, OB-GYN, or breast radiologist about the right schedule for you.
4. Colorectal Cancer
Colorectal cancer is one of the most common cancers in adults, and obesity increases your risk. Screening should begin at age 45 for average-risk individuals. Options include colonoscopy, Cologuard (a stool DNA test), or FIT testing — so there are low-barrier options available. If you have a strong family history of colorectal cancer, or if you live with Crohn's disease or ulcerative colitis, you may need to start screening earlier. Don't wait.
5. Pancreatic Cancer
Pancreatic cancer is particularly difficult to detect early because it often causes few symptoms. One early sign can be feeling full on less food than usual — which can also occur with GLP-1 receptor agonist medications (like semaglutide or tirzepatide). If you are on a GLP-1 medication and experience significant unexplained fullness, unintentional weight loss, or abdominal pain, bring this to your doctor's attention promptly. Imaging of the abdomen may be warranted to rule out pancreatic pathology.
6–13. Additional Obesity-Associated Cancers
The following cancers are also associated with obesity, though routine screening guidelines do not currently exist for most of them in the general population. Being aware of new or unusual symptoms — and discussing any concerns with your doctor — is the best approach:
- Kidney (renal cell) cancer
- Gastric (stomach) cancer
- Gallbladder cancer
- Thyroid cancer
- Meningioma (a type of brain tumor)
- Multiple myeloma (a blood cancer)
- Ovarian cancer
- Esophageal adenocarcinoma
Who Is at Greatest Risk?
The relationship between obesity and cancer is not the same for everyone. Several factors compound or amplify this risk:
Women Face a Higher Relative Risk
About 5% of cancers in men are linked to obesity, compared to 11% of cancers in women. This significant difference is largely hormonal — many obesity-related cancers in women are driven by excess estrogen produced by adipose tissue. For women with PCOS, metabolic syndrome, or insulin resistance, this hormonal picture can be especially complex.
Duration Matters
The longer someone has lived with obesity, the higher their cumulative cancer risk. Adults who have struggled with weight since childhood or young adulthood carry a greater lifetime risk than those who develop obesity later in life. This is an important reason to address metabolic health proactively — not just for how you feel today, but for your long-term cancer risk.
Race and Ethnicity
Non-white populations face a disproportionately higher risk of obesity-related cancers, due to a combination of genetic factors and the structural health disparities embedded in our healthcare systems. This is an area where equitable, accessible care — like telehealth — can make a real difference.
Obesity Plus a Metabolic Condition
If you are living with both obesity and a metabolic condition — such as type 2 diabetes, prediabetes, PCOS, or metabolic syndrome — your risk of developing obesity-related cancers is further elevated. This is a key reason why treating the whole metabolic picture matters, not just one condition in isolation.
Obesity Affects Cancer Outcomes Too — Not Just Risk
Even when obesity doesn't cause a cancer, it affects how that cancer behaves and how well patients do. Research shows that individuals with cancer who have a BMI of 40 or greater face significantly worse outcomes:
- Men with a BMI ≥ 40 have approximately a 50% higher mortality compared to those with a BMI ≤ 25
- Women with a BMI ≥ 40 have approximately a 60% higher mortality compared to their lower-BMI counterparts
This underscores why treating obesity as a serious medical condition — not a cosmetic concern or a willpower issue — is so critical.
Why Does Obesity Increase Cancer Risk? The Science Behind It
Fat cells (adipose tissue) are biologically active. They are not inert storage units — they produce hormones, inflammatory signals, and chemical messengers that circulate throughout the body. Here's how those factors connect to cancer:
Insulin and growth signals: Obesity is associated with elevated insulin levels and insulin resistance. Elevated insulin acts as a growth signal, which can encourage abnormal cells — including cancer cells — to proliferate.
Leptin and adiponectin imbalance: Adipose tissue produces leptin (elevated in obesity) and adiponectin (reduced in obesity). Leptin can promote cancer cell growth, while reduced adiponectin removes a protective brake on that growth.
Excess estrogen: Adipose tissue converts androgens into estrogen. In postmenopausal women especially, this extra-ovarian estrogen production is a major driver of estrogen-sensitive cancers like endometrial and breast cancer. For women with PCOS, who often already have hormonal dysregulation, this adds another layer of complexity.
Chronic inflammation: Obesity drives a state of low-grade, chronic systemic inflammation. That persistent inflammatory environment can promote DNA damage and create conditions that allow cancer cells to grow unchecked.
What You Can Do: Practical Next Steps
This information is not meant to alarm you — it's meant to empower you. Here's what you can do today:
1. Get your cancer screenings on schedule. Colon cancer screening at 45. Breast cancer screening at 40. Ask your doctor about hepatitis B/C testing and liver ultrasounds if you have fatty liver disease. Don't skip preventive care because life gets busy.
2. Treat your metabolic health as a priority. Managing obesity, prediabetes, insulin resistance, PCOS, and metabolic syndrome isn't just about weight or blood sugar — it's about reducing your lifetime cancer risk, cardiovascular risk, and overall mortality. Lifestyle changes and safe, effective medications can meaningfully shift that risk.
3. Know your symptoms. Unexplained weight loss, persistent abdominal pain or fullness, unusual bleeding, or new lumps or masses should always be evaluated. Don't wait and see. These symptoms warrant a conversation with your doctor.
4. Ask for help — it's available. Obesity is a chronic disease with biological underpinnings. It is not a personal failure. Whether through lifestyle coaching, GLP-1 medications, or other evidence-based treatments, there are more tools available today than ever before.
How Missouri Metabolic Health Can Help
At Missouri Metabolic Health, we take a whole-person approach to metabolic care. As a board-certified family medicine and obesity medicine physician, Dr. Lindsay Ogle partners with patients to address the root causes of metabolic dysfunction — not just manage individual lab values.
We work with adults living with:
- Obesity
- Prediabetes and type 2 diabetes
- Metabolic syndrome
- PCOS (polycystic ovarian syndrome)
- Fatty liver disease
- And other metabolic conditions
Our approach combines lifestyle optimization (nutrition, movement, sleep, stress management) with safe and effective medical treatments, including GLP-1 receptor agonists and other evidence-based medications when appropriate.
We are a telehealth clinic, which means you can access expert metabolic care from the comfort of your home — no matter where you are in Missouri.
Ready to Take Control of Your Metabolic Health?
If you're ready to address your weight, blood sugar, hormonal health, or metabolic risk factors — we're here to help. Reducing your cancer risk, protecting your heart, and feeling better in your body are all achievable goals with the right support.
[Book your consultation with Missouri Metabolic Health today →]
This post is intended as general medical education and not as direct medical advice. Please speak with your own physician about your individual health situation and appropriate cancer screening for you.
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