Roughly 1 in 10 new cancer diagnoses in the United States each year may be attributable to overweight and obesity, according to a translational science review published in JAMA in 2026.
The review was led by Neil Iyengar, MD, of Winship Cancer Institute at Emory University, alongside colleagues at Memorial Sloan Kettering Cancer Center and the University of Kansas Medical Center. They synthesized evidence from cell, animal, and population studies.
For some cancers the link is far stronger. The authors report that up to 50 percent of endometrial and hepatobiliary cancers, which involve the liver, gallbladder, and bile ducts, are associated with excess weight.
In total, the review connects overweight and obesity to at least 13 cancer types, including postmenopausal breast, colorectal, pancreatic, ovarian, kidney, esophageal, gastric, prostate, thyroid, and multiple myeloma.
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How fat tissue changes cancer risk
Excess body fat is not inert storage. It behaves as an active organ that can drive chronic inflammation, alter hormones such as estrogen and leptin, weaken the immune system's tumor surveillance, and disrupt the gut microbiome.
Together, these shifts create an internal environment where cancer cells can arise, survive, and multiply more easily. "Nearly every process that leads to the development of cancer in our bodies is accelerated by obesity," Iyengar told Healthline.
Why 10 percent weight loss is a meaningful threshold
Small changes on the scale may not move the biology much. The JAMA review concluded that reductions greater than about 10 percent of body weight may be needed to meaningfully shift the metabolic and inflammatory processes that link excess weight to cancer risk.
That figure sets a higher bar than many people expect. It also matters for how doctors talk about prevention, since goals under that level may improve general health without significantly lowering cancer-specific risk.
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Where medication and surgery fit in
Alongside diet and exercise, the authors flag two medical options being studied specifically for cancer risk reduction. These are bariatric surgery and GLP-1 receptor agonists, a drug class that includes semaglutide, the active ingredient in Novo Nordisk's Ozempic and Wegovy.
In clinical trials, GLP-1 medications have produced average weight losses in the range of 15 to 20 percent, according to Healthline's reporting on the review. That level of weight loss sits above the 10 percent threshold the researchers highlight.
The review does not recommend that individuals start any specific treatment. People with concerns about their weight or their cancer risk should raise the question with their own doctor, who can weigh the evidence against their personal health history.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.