Now, there is another reason why we need to maintain a healthy weight as we get older. An international research team has determined that eight other types of cancer are associated with overweight and obesity: stomach, liver, gallbladder, pancreas, ovary, meningioma (a brain tumor), thyroid cancer, and a type of multiple myeloma Blood cancer. Limiting age-related weight gain can help reduce the risk of these cancers, the data suggests.
The survey results, published in the New England Journal of Medicine, are based on a World Health Organization’s International Agency for Research on Cancer (IARC) review of 1,000 overweight people and their cancer risks. The cancer research institute is headquartered in France.
This discovery may have a significant impact on the global population. Globally, there are an estimated 640 million obese adults and 1.1 million obese children, including one third of American adults and children.
In 2002, the same group of cancer researchers found sufficient evidence that excess weight is related to these cancers: colon, esophagus, kidney, breast and uterine cancers.
"Lifestyle factors, such as healthy eating, maintaining a healthy weight and exercise, and not smoking, can all have a significant impact on reducing cancer risk," said Colditz. "If public health is to fight cancer, it should be concerned about everyone. Things that have a certain degree of control."
"But losing weight is difficult for many people," he added: "Instead of discouraging and giving up on obese people, those struggling to lose weight can instead focus on avoiding weight gain."
For most cancers on this new expanded list, the researchers pointed out a positive dose-response relationship: the higher the body mass index, the greater the cancer risk.
Cancer risk is related to overweight, which is consistent among men and women, and when data is available, the results are consistent across geographic regions—North America, Europe, Asia, and the Middle East.
There are many reasons why being overweight or obese increases the risk of cancer, the researchers pointed out. Excess fat leads to overproduction of estrogen, testosterone and insulin, and promotes inflammation, all of which can drive cancer growth.
"The number of obese people in the U.S. and even the world is considerable," Colditz said: "This is another wake-up call. Now, it is time to take our health and diet seriously."