The most overweight people have more than double the risk of developing cancer, a major study on obesity has shown.
Already known to be a red flag for many cancers, clear evidence has now been revealed exposing the most overweight people to a greater risk of the disease.
Researchers from the Department of Translational Medicine at Lund University, Malmo, Sweden, found rapid weight gain in particular was more closely associated with a higher incidence of cancer.
The new research presented at the European Congress on Obesity in Istanbul explored body weight trajectories in more than 630,000 people aged 17 to 60, from 1963 until 2023.
Each person had four weight measurements at incremental stages throughout life.
For all cancers combined, the increased risk of cancer in the highest 20 per cent was seven per cent for men and 17 per cent in women, whereas for established obesity-related cancers the increased risk was 46 per cent for men and 43 per cent in women.
Study author, associate professor Anton Nilsson, said early weight gain in childhood was more likely to lead to higher weight gain in adults.
“That means that an early weight gain is associated with a larger cumulative exposure to obesity and body fat,” he said. “If you have a more relative exposure across your lifetime, the incidence of cancer increases.
“Our study does not speak specifically about interventions or behaviours, but weight gain is associated with higher risk, so it should be avoided.”
Over-30s risk
Women who gained weight over the age of 30 were more vulnerable to disease related to sex hormones, such as endometrial cancer, postmenopausal breast cancer and meningioma, in the brain and spine.
Obese men under the age of 45 were more likely to have cancers related to chronic inflammation, insulin resistance and gastroesophageal reflux disease. These cancers include oesophageal and liver cancer.
Men who developed obesity before the age of 30 had five times the risk of liver cancer, a doubled risk of pancreatic cancer and renal cell cancer, and a 58 per cent increase in their risk of colon cancer, compared with men who never had obesity.
Meanwhile, women who developed obesity before age 30 years were at 4.5 times increased risk of endometrial cancer, a 67 per cent higher risk of pancreatic cancer, a doubled risk of renal cell cancer and a 76 per cent increased risk of meningioma.
Co-author, assistant professor Tania Stocks, said steeper increases in body weight between ages 17 and 60 were associated with a higher incidence of several established obesity-related cancers.
“Both early adult body weight and weight gain across adulthood were associated with the risk of most established and some potentially obesity-related cancers, with differences by cancer site, sex and timing of weight gain,” she said.
“In the context of the rising prevalence of obesity and cancer in Western countries and globally, the findings highlight the importance of a life-course perspective on weight management for cancer prevention.”
Obesity affects one in eight people globally and is recognised as a leading cause of cancer.
Cancer has already been strongly associated with obesity, with the International Agency for Research on Cancer (IARC) showing evidence connecting excess body weight with multiple cancers, including those in the stomach, colorectum, liver and thyroid. Further evidence suggests potential links to blood cancers.
Top-three killer
Cancer is the third leading cause of death in the UAE, with obesity and smoking significant contributors to mortality rates.
Breast, colorectal, thyroid and leukaemia are the most common cancers, with rising cases also linked to an ageing population. In 2021, 5,830 new cases of cancers were reported, with more screening programmes and AI-supported diagnostics leading to more cases being identified.
Dr Yasmeen Ajaz, a consultant endocrinologist at Medcare Hospital Al Safa, said maintaining a healthy weight is proven and effective in protecting against ill health.
“This study strengthens the case for viewing sustained healthy body weight as a powerful, modifiable tool for cancer prevention,” he said. “In my practice, I emphasise that metabolic health, such as insulin sensitivity and reduced inflammation, often matters as much as the number on the (weight) scale.
“Patients who achieve and maintain better weight trajectories see improvements not just in cancer risk, but across diabetes, cardiovascular disease, non-alcoholic fatty liver disease and quality of life.”
