Scientists have found that obesity increases risk of 13 different cancers in young adults.
The meta-analysis describes how obesity has shifted certain cancers to younger age groups, and intensified cellular mechanisms promoting the diseases.
Cancer typically associated with older adults over 50 are now reported with increasing frequency in young adults, said the researchers at Case Western Reserve University in the US.
In 2016, nearly one in 10 new breast cancer cases, and one in four new thyroid cancer cases were in young people aged 20-44, according to the study published in the journal Obesity.
Young people with body mass indexes (BMIs) over 30 are more likely to experience aggressive malignancies, said Nathan A Berger from Case Western Reserve University.
"If you are obese, you are at a higher risk of cancer. If you lose weight, it improves the prognosis and may lower your risk, but it never goes away completely," Berger said.