Experts have proposed lowering the obesity threshold after discovering that millions of people with a ‘normal’ BMI are at risk of multiple cancers.
Two major studies found that men with a body mass index between 20 and 22.5 were at an ‘increased’ risk of developing eight forms of the disease in their lifetime, including head and neck cancer, pancreatic cancer and liver cancer.
BMI is a rough measurement of how much body fat a person has compared to their height. A healthy range is between 18.5 and 24.9, while 25 to 29.9 is considered overweight, and anything over 30 is considered obese.
Researchers in Sweden followed more than 1.5 million men from their teenage years for almost 40 years, looking for links between teenage weight and future cancer risk.
They found that those who were overweight or obese (a BMI of at least 25) at age 18 were more likely to develop 17 different cancers, including head and neck, brain, thyroid, bladder and liver cancer.
The researchers predicted how many cases of cancer in the US and Sweden will be attributable to high BMI, and how many cases will be attributed to high BMI by 2050.
Young men with a ‘normal’ BMI, but also people who are overweight or obese, are at risk of eight to seventeen forms of cancer
But those with a ‘normal’ BMI were also up to 49 percent more likely to develop eight cancers: head and neck cancer, esophageal cancer, stomach cancer, pancreatic cancer, liver cancer, kidney cancer, melanoma and non-Hodgkin’s lymphoma.
The researchers suggested that because of these increased risks, “normal” weight for young adults should be redefined.
Dr. Maria Åberg, senior author of both studies and professor of general medicine at the University of Gothenburg in Sweden, said: ‘This suggests that the current definition of ‘normal’ weight may primarily apply to older adults, while optimal weight is considered standard can apply. young adults are probably in a lower range.”
Studies in children have suggested that obesity in children damages the immune system and causes cellular changes that make the body vulnerable to cancer later in life – even if they lose weight.
In the pair of studies, published in the journals Obesity And Cancer MedicineÅberg’s team evaluated 1,489,115 Swedish men between 1968 and 2005, starting when they were 18 years old.
About 84,621 people were diagnosed with cancer during that period.
Overweight and obese men were more likely to develop 17 cancers, including lung, head and neck, brain, thyroid, pancreatic, colorectal, kidney and bladder cancers, as well as melanoma, leukemia, myeloma and lymphoma.
The risk was highest for abdominal cancer, such as esophageal, stomach and kidney cancer, with a three to four times greater risk.
The studies also found that overweight or obese men were two to three times more likely to die within five years of being diagnosed with Hodgkin’s lymphoma and skin, thyroid, bladder and prostate cancer.
They were 1.4 to two times more likely to die from cancer of the head, neck, rectum and kidneys.
Study author Aron Onerup said: ‘Overweight and obesity at a young age appear to increase the risk of developing cancer, and we see links between unhealthy weight and cancer in almost every organ.’
‘Given the alarming trend of obesity in childhood and adolescence, this study reinforces the need to deploy strong resources to reverse this trend.’
In August, the same research team published a study in the British Journal of Sports Medicine, which evaluated men who had signed up for mandatory military service. The researchers found that men with lower cardiorespiratory fitness (CPF) were at greater risk for several types of cancer.
An investigation was launched in July Nature communication found that Spanish adults who were overweight or obese before age 40 were at greater risk for 18 types of cancer, including leukemia, non-Hodgkin’s lymphoma, bladder, head and neck cancer.
They found that men who were overweight or obese (a BMI of at least 25) at age 18 were more likely to develop 17 different cancers, including head and neck, brain, thyroid, bladder and liver cancer.