Food portions are growing in the U.S. and all over the world. It’s easy to get your hands on a super-sized burger, fries, and a humongous sugary fountain drink from multiple fast food chains. As food portions get larger, obesity rates go up, and so does the risk of cancer. A new study reports that obesity can increase your risk of getting 10 of the most common cancers.

The new research, published in the journal The Lancet, also says that your body mass index (BMI) is a key indicator of your risk of getting cancer. The Centers for Disease Control and Prevention defines BMI as a number calculated by your height and weight that indicates how much fat you have on your body. This number helps to determine if you are obese or overweight. A healthy BMI for adults is between 18.5 and 24.9. You would be classified as overweight if your BMI is 25, and obese if your BMI is over 30.

For the study, the newest and largest linking obesity to cancer, researchers from the London School of Hygiene and Tropic Medicine monitored health changes in five million people in the UK over the course of seven years. After analyzing health data of all participants, scientists found that for each estimated 29 to 35 pounds (13-16kg) gained, the risk of six cancers increased. Cancer of the uterus posed the highest risk, followed by cancer of the gallbladder, kidney, cervix, and thyroid. Leukemia had the lowest risk.

The report also found that people with a high BMI were not only at risk for the six cancers mentioned, but it also increased their risk of four more cancers, including liver, colon, ovaries, and post-menopausal breast cancer, a total of 10 cancers. Researchers cited in their study that obesity increased the risk of the most common cancers, but they also found that those with a high BMI reduced their risk of prostate cancer.

Scientists also reported that BMI was associated with 17 of the 22 cancers they studied. Results showed that the impact of the BMI varied depending on the cancer. "For example, risk of cancer of the uterus increased substantially at higher body mass index. For other cancer we saw a more modest increase in risk or no effect at all,” Dr. Krishnan Bhaskaran, who led the research, told the BBC.

Despite the varied results, one thing was clear: Obesity is very harmful to the health and is a big risk factor for many cancers. According to the CDC, one third of adults are obese and 17 percent of children are obese. Researchers encourage a balanced diet and regular exercise as a way to stay healthy and help reduce your risk of getting cancer.

Source:  Bhaskaran K, Douglas I, Forbes H, dos-Santos-Silva I, Leon D, Smeeth L. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5.24 million UK adults. The Lancet. 2014.