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A large international study has strengthened the evidence that excess body weight can raise the risk of several types of cancer. Researchers reviewed decades of peer-reviewed literature around the world and found that a higher Body Mass Index (BMI) is linked to an increased risk of 19 different cancers.
The findings were published in the journal Nature Metabolism on June 15, 2026.
The new review analysed information from 226 studies involving about 1.5 million documented cancer cases.
The study found that a higher BMI, an estimate of body fat based on a person’s height and weight, is positively linked to 19 distinct cancer types.
Some of the strongest links were seen for endometrial cancer, which affects the lining of the uterus, and oesophageal adenocarcinoma, a type of cancer that develops in the food pipe. According to the analysis, every five-unit increase in BMI was associated with a 58 per cent higher risk of endometrial cancer and a 47 per cent higher risk of oesophageal adenocarcinoma.
The review also found links between higher BMI and several cancers that have received less attention in the past. These included leukaemia, non-Hodgkin lymphoma, bladder cancer and glioma, a type of brain tumour. Researchers say these findings expand current understanding of how excess body weight may influence cancer development.
At the same time, the researchers observed some inverse associations. Higher BMI was linked to lower risks of premenopausal breast cancer, lung cancer among never-smokers, and esophageal squamous cell carcinoma in never-smokers. These contrasting findings highlight the complex biological relationship between body weight and cancer and suggest that different mechanisms may be involved depending on cancer type and population group.
The study also revealed notable geographic and sex-related differences. For example, the obesity-associated risk of postmenopausal breast cancer was approximately double the excess risk in East Asian populations compared to their European populations.
For colorectal cancer, the association with obesity was substantially stronger in men, whereas for gallbladder cancer the relationship was more pronounced in women.
Researchers emphasise that obesity remains one of the most important modifiable risk factors for cancer. Excess body fat can alter hormone levels, including insulin and oestrogen, promote chronic inflammation, disrupt metabolism and create conditions that encourage abnormal cell growth.
Obesity rates have been rising worldwide, making these findings particularly important.
Globally, obesity rates have been increasing steadily over the last three decades. In almost every region, there are now more people living with obesity than underweight, and if current numbers continue to rise, as many as 1 billion adults, or 12 per cent of the world population, will be living with obesity by 2025.
Researchers note that regions such as South Asia and Africa remain underrepresented in long-term cancer studies and call for more research involving diverse populations to better understand obesity-related cancer risks worldwide.
