Study Links Obesity to Increased Cancer Risk

A growing body of scientific research shows a strong link between obesity and an increased risk of various types of cancer, sparking concern among public health experts. According to a fact sheet from the U.S. National Cancer Institute, excess adipose tissue (fat) may drive cancer development through hormonal changes, inflammation, and insulin dysregulation. Studies suggest that obesity promotes elevated levels of insulin and insulin-like growth factor‑1 (IGF-1), which are associated with higher risks for cancers such as colorectal, breast, kidney, and endometrial.
A large pooled European cohort study looked at body mass index (BMI) and weight changes over time in more than 220,000 participants, finding that long-term overweight and obesity significantly raised the risk for obesity-related cancers. The timing and duration of weight gain also mattered — those who were already overweight before age 40 had a notably higher risk of developing cancers like endometrial cancer and renal cell carcinoma.
On a broader scale, a massive Swedish cohort — covering more than 4 million people — found that higher BMI was linked with elevated risks of over 100 cancer forms and subtypes. This research builds on decades of epidemiological findings: meta-analyses going back to the 1980s have consistently shown that obesity raises the risk for cancers of the colon, esophagus, pancreas, kidney, and postmenopausal breast, among others.
Mechanistically, scientists point to chronic inflammation, hormonal imbalances (especially increased estrogen in fat tissues), and growth-factor signaling pathways that fuel tumor development in people with obesity. Importantly, research also suggests that weight loss — such as through bariatric surgery or the use of certain glucose‑lowering drugs — may reduce cancer risk, highlighting the potential benefit of interventions aimed at reducing obesity.