Does eating a lot of sugar increase my chances of getting cancer?
Drinking a lot of sugary drinks is associated with a higher chance of breast, prostate, and bowel cancer. Whether sugar itself is the cause is not yet certain, but the studies do give reason to limit your soft-drink intake.
Sugary drinks are linked to a higher risk of certain cancers in several large studies. For breast cancer, the link amounts to a 14% higher chance with high consumption; for prostate cancer, 18% higher. For bowel cancer, data from more than 557,000 participants combined point to a 17% higher chance. But whether sugary drinks actually cause that cancer, or whether other factors are at play, has not been proven: these are associations from studies where people were followed for years, not direct cause-and-effect relationships.
Fructose deserves separate attention. Each extra 25 grams of fructose per day was associated with a 22% higher chance of pancreatic cancer. That sounds like a lot, but the evidence behind that figure was weak. For bowel and pancreatic cancer at typical soft-drink consumption levels, a link was visible but not strong enough to draw firm conclusions.
Artificial sweeteners do not appear to pose a separate problem: studies covering many types of cancer found no consistent link with substances such as aspartame or sucralose. Worth noting: that research was funded by the American beverage industry, which may make the results look more favourable. Keep that in mind.
What you put on your plate matters too. Plant-based eating patterns, which naturally contain little added sugar, were associated with a lower cancer risk. That is also an association, however: people who eat a lot of vegetables and fruit generally live more healthily in several other ways as well.
This answer draws on several large combined summaries of studies in which people were followed over time, including one that covered more than 557,000 people. All evidence is based on associations, not proven cause and effect. The quality of the evidence ranged from low to moderate; the researchers behind the broad sugar review (2023) rated the associations for cancer as mostly low quality, and the strongest associations in that study were for heart disease, not cancer. The study on artificial sweeteners was funded by the American beverage industry, which is a conflict of interest that may have influenced the results.
Does being overweight increase my risk of cancer, and if so, which types?
Excess weight increases your risk of at least 13 types of cancer, including uterine, colorectal, breast and liver cancer. Losing weight reduces that risk, although it remains unclear whether all methods of weight loss are equally effective for immune defence against cancer.
Does having type 2 diabetes increase your risk of certain cancers?
Research shows that type 2 diabetes is associated with a higher risk of certain cancers, and that link runs largely through the excess weight that often accompanies it. For most cancers, commonly used diabetes medicines show no raised risk.
Does sitting a lot increase my risk of cancer, even if I exercise?
Sitting a lot increases your risk of certain cancers, even if you exercise. In addition to moving regularly, try to reduce your sitting time itself, because the two only partially compensate for each other.
Does eating burnt food increase your risk of cancer?
Burnt or heavily grilled meat contains substances that cause cancer in animal studies, but whether ordinary exposure measurably increases cancer risk in humans has not yet been proven. Those who want to limit the risk should more often choose boiling or steaming over grilling, and leave blackened pieces aside.
Does poor sleep increase my risk of cancer?
Poor sleep, and sleep apnea and night-shift work in particular, is associated with an increased cancer risk. Whether you personally face a higher risk depends on which sleep problems you have; at the very least, have any apnea symptoms evaluated.
Does a large belly increase my risk of cancer more than being simply overweight?
A large belly raises the risk of several types of cancer more than being simply overweight, especially in men. Having your waist circumference measured is therefore more meaningful than watching the scales alone.