A diagnois of cancer can shatter your world. In a fair number of cases, though you may have felt unwell, or had some symptoms, getting the diagnosis can be shocking. Research on cancer continues to uncover new risks, we do know some clear contributing factors to specific cancers. If you smoke, you have a significantly elevated risk of developing lung cancer. If you were exposed to asbestos, your risk of mesothelioma is elevated. Studies have also confirmed that being overweight or having obesity raises your risk for several cancers. They include breast, colon, rectal, uterine, esophageal, gallbladder, kidney, liver, ovarian, pancreatic, stomach, thyroid, brain and spinal cord cancers, as well as certain blood cancers. Some research has suggested a link to prostate tumors and oral cancers.

Between 1975 and 2016 there was an uptick in rates of obesity among children and adults. This steady rate of increase has affected industrialized nations, as well as poorer nations where starvation used to be more of the norm. Worldwide during that time period, the prevalence of obesity in men quadrupled, and it doubled in women. During those decades, the number of obese adults worldwide grew from 100 million to 671 million. In 2012, excess weight was linked to 544,300 cancers worldwide.

In low income countries, the link accounted for one percent of all cancers, while in high income countries (Western countries, Middle Eastern and North African countries) the link was attributed to seven to eight percent of all cancers. As of 2016, 40 percent of adults (that’s nearing half the world population) and almost 20 percent of kids worldwide are overweight or clinically obese. That’s two billion adults and 340 million children worldwide who are carrying serious levels of excess weight!

Obesity risk has been linked more predominantly to wealthier nations, but it is less common in some affluent Asia-Pacific countries. This may be a result of healthier diets – eating more fish and vegetables, eating smaller portions and actively walking to work and to other activities. If someone from that area of the world move to the U.S., obesity would likely “catch up with them” simply because of the abundance of unhealthy foods and the use of cars and mass transit for transportation as part of their new lifestyle.

Researchers agree that a significant cause of the obesity surge can be attributed to changes in the global food system during the highlighted decades. High calorie, poor quality food with reduced opportunities (and desire) to move physically daily has helped to fuel the obesity crisis. There are now enough studies identifying the obesity-cancer link for it to be discussed during routine office visits. Any patient presenting with a diagnosis of being overweight or having obesity will typically hear about elevated risk of high blood pressure, heart disease, and diabetes. We now need healthcare providers to highlight this serious cancer risk as well.

What’s especially challenging is the fact that obesity impact is a slow train. You gradually gain weight in most cases and that excess weight that builds up year after year, slowly feeds cancer cells. It can be hard to convince someone to lose weight, when the excess weight causes “invisible changes” in the body at the cellular level. It takes time for a cancer to form and if you have no symptoms, you have no “skin in the game” to work on your weight issues. And, it’s also really hard to lose weight and keep it off, for good. Cancer risk should at minimum inspire a conversation about your weight between you and your healthcare provider. It should certainly inspire you to undergo age-appropriate cancer screenings, given your heightened risk.