Weighing Up the Cancer Problem
One of the most effective ways a person can lower his or her risk of developing cancer is by maintaining a healthy weight. This is because being overweight or obese increases the chance that a person will develop 11 types of cancer and is estimated to be responsible for about one-third of cases of the most commonly diagnosed types of cancer in the United States.
People who are obese or overweight are at increased risk
for 11 types of cancer.
Despite the adverse health risks of being overweight or obese, federal data show that 71 percent of U.S. adults age 20 or older are overweight or obese, as are 32 percent of U.S. youth ages 2 to 19. These numbers have been rising steadily for the past two decades: In the mid-1990s, just 55 percent of U.S. adults and 23 percent of youth were overweight or obese.
Global numbers have been rising too. In fact, the worldwide prevalence of obesity more than doubled between 1980 and 2014, at which point, it is estimated that 1.9 billion adults age 18 and older and 42 million children under the age of 5 were overweight or obese. By 2025, 70 million children worldwide are expected to be overweight. Here is a look at 11 types of cancer in which risk is affected by overweight or obesity:
How Can We Reverse the Rising Tide of Obesity and Overweight?
Consuming Fewer Calories
Given that weight gain occurs when a person consumes more calories than they burn, one approach to tackling the obesity epidemic is through public education initiatives to promote healthy dietary practices. To this end, the U.S. Department of Health and Human Services and U.S. Department of Agriculture routinely convene a committee of researchers in the fields of nutrition, health, and medicine, to rigorously analyze the available scientific evidence and help the agencies develop dietary guidelines. The agencies released the latest edition of the guidelines, the 2015 – 2020 Dietary Guidelines for Americans, just last year. It emphasizes:
- Following a healthy eating pattern throughout life;
- Consuming a variety of nutrient-dense foods in recommended amounts;
- Limiting calories from added sugars and saturated fats and reducing sodium intake;
- Shifting to healthier food and drink choices; and
- Supporting healthy eating patterns for all.
In May, the U.S. Food and Drug Administration announced complementary changes to food labeling regulations in an effort to help people make better-informed food choices and meet the 2015 – 2020 Dietary Guidelines for Americans. The most prominent change is that nutrition facts labels on food packaging will have to include information about how much sugar has been added to the food product by July 26, 2018. This should help people meet the dietary guidelines recommendation to limit intake of calories from added sugars to less than 10 percent per day. Although the number of calories each person needs varies depending on gender and lifestyle, on average this translates to about 12.5 teaspoons of added sugar per day. Currently, the average person in the United States consumes more than 13 percent of his or her calories from added sugars each day, which on average is about 16.5 teaspoons of added sugar. As a reference point, one 12-ounce can of soda has about 8 teaspoons of added sugar.
The recent focus on added sugars is based on research showing that a diet high in added sugar can lead to obesity.
The main source of added sugars in U.S. diets is beverages, including soft drinks, fruit drinks, sweetened coffee and tea, energy drinks, alcoholic drinks, and flavored waters. In an effort to reduce the consumption of sugar-sweetened beverages, several cities and states have proposed taxes on these drinks. Most of these measures have failed to gain enough support to pass, even though researchers estimate that a 0.04-cent-per-calorie tax on sugar-sweetened beverages, which is equivalent to about 6 cents per 12-ounce can of soda, could reduce the average person’s consumption of calories from sugary drinks by about 5,800 per year. The notable exception is Philadelphia, which became the first major U.S. city to vote to approve a tax on soda and sugar-sweetened beverages on June 16.
Increasing Calories Burned
The other way to address the obesity epidemic is to increase the other side of the energy balance equation —physical activity. The added bonus of physical activity is that it not only helps a person maintain a healthy weight, it also decreases the person’s risk of many types of cancer independent of its effect on weight. In fact, the most recent research on this topic found that leisure-time physical activity, meaning physical activity undertaken outside of the workplace and as a result of transportation needs, was associated with significantly reduced risk of 13 types of cancer, including breast, colorectal, and lung cancer. Moreover, the risk-reduction effects were evident for 10 of these cancers regardless of body size.
Despite the clear benefits of physical exercise, more than half of U.S. adults and 73 percent of high school students do not meet the relevant recommended guidelines for aerobic physical activity.
Several steps to promote physical activity for all segments of the U.S. population are outlined in Step it up! The Surgeon General’s Call to Action to Promote Walking and Walkable Communities and in the U.S. National Physical Activity Plan. However, concerted efforts by individuals, families, communities, schools, workplaces, institutions, health care professionals, media, industry, government, and multinational bodies are required to implement any strategy to promote the maintenance of a healthy weight and the participation in regular physical activity.
In addition, more research is needed to understand why some individuals are refractory to current public education and policy initiatives. One recent study suggested that the way in which public education messages are framed can dramatically influence whether or not an individual modifies his or her behavior because it showed that individuals who were dieting who saw a message focusing on the negative aspects of unhealthy food actually increased their consumption of unhealthy foods.
Benefits Beyond Cancer
Being overweight or obese increases the chance that a person will develop many other long-term medical conditions in addition to 11 types of cancer, including heart disease, kidney disease, type 2 diabetes, stroke, and osteoarthritis. Moreover, the World Health Organization states that people who are more active have lower rates of all-cause mortality, coronary heart disease, high blood pressure, stroke, type 2 diabetes, metabolic syndrome, certain types of cancer, and depression compared with those who are less active.
Thus, we need new and better ways to help people modify their behaviors in order to maintain a healthy weight, become physically active, and eat a healthy diet. That could have an enormous impact on reducing cancer risk and improving public health worldwide.