Obesity is a leading factor in approximately 4 percent of worldwide cancer cases, according to data published in the latest issue of the American Cancer Society's CA: A Cancer Journal for Clinicians publication.
Excessive weight has been linked to an increased risk of developing 13 types of cancer including: breast, uterus, esophagus, gallbladder, kidney, liver, ovary, pancreas, stomach, thyroid, blood cells, colon and rectum, and brain and spinal cord. New research suggests that the likelihood of developing prostate tumors and cancers of the mouth and throat may, too, be triggered by obesity.
The journal states: "Although the effects of excess body weight on cancer risk are modest for most cancer sites, excess body weight is highly prevalent in high‐income countries and elsewhere, leading to a substantial burden of cancers. In 2012, it was estimated at 544,300 cases, or 3.9 percent of all cancers worldwide, and this number undoubtedly will rise in the coming decades given current trends."
To define obesity, the journal's authors cite the World Health Organization's (WHO) rules on body mass index (BMI). BMI is calcuated as body mass (in kilograms) divided by square height (in meters). According to WHO, adults with a BMI below 18.5 kg/m2 are underweight, while those with a BMI between 18.5 kg/m2 and 24.9 kg/m2 are normal and those with a BMI between 25 kg/m2 to 30 kg/m2-plus are obese.
In 2016, about 40 percent of the world's adults and 18 percent of children were obese, equating to almost 2 billion adults and 340 million children. This trend currently contributes to four million weight-related deaths every year, as well as $2 trillion in negative economic impact.
Obese adults comprise only 1 percent of the cancer population in low-income countries, while they account for at least 7 percent of the cancer population in several high-income Western countries.
“The simultaneous rise in excess body weight in almost all countries is thought to be driven largely by changes in the global food system, which promotes energy-dense, nutrient-poor foods, alongside reduced opportunities for physical activity,” lead journal author Hyuna Sung told Reuters in December 2018. Sung noted that the pronounced obesity surge in select low- and middle-income countries is related to those populations' adoption of Western lifestyles—too little exercise, and too much unhealthy food.
In any given country, there is a 0.4 increase in the average adult's BMI for each $10,000 increase in mean per capita national income, the journal states.
The topics of obesity and physical inactivity were the subject of numerous high-profile research reports issued in 2018. Physical inactivity is currently the most overlooked issue in the health and wellness industry, according to an August 2018 report by PHIT America. Furthermore, one in four of the world's adults do not receive adequate exercise, according to research published in September 2018 by WHO.
An August 2018 study published in Lancet Public Health suggests low-carb diets—popular for rapid weight loss—can, in fact, be detrimental to one's life expectancy.
To view the full report from the recent CA journal, click here.