The Obesity Epidemic — It’s Not a Small World After All
By Rita E. Carey, MS, RD, CDE
Today’s Dietitian
Vol. 8 No. 10 P. 24

The weight of the world is posing a hefty problem.

We have all heard the statistics: An estimated 65% of Americans are overweight or obese and the current course of communal weight gain shows no sign of abating. Equally disturbing is the fact that people around the world are getting heavier as many European and other nations follow a similar pattern of “growth.” Theories abound as to why this trend is occurring. These include, but are clearly not limited to, reduced physical activity, increased consumption of energy-dense meals and snacks, food insecurity, and the loss of traditional, cultural rituals linked with food. Many studies and surveys have been conducted to determine how to reverse this global epidemic, and the data offer at least some insight into the ways both human lifestyles and bodies are changing worldwide.

Obesity in the United States and the World
The increased prevalence of individuals who are overweight and obese in the United States and Europe, as well as South America and Asia, has made thinning, or even stable weight, populations the exception rather than the norm. Though the United States leads the pack in the rate of weight gain over the longest period of time, Spain, Portugal, Ireland, Greece, Great Britain, Italy, Poland, Finland, and, yes, even France are showing a similar, if slower, trend.1-10 In fact, over the last decade, mean body mass index (BMI) has increased in virtually all Western European countries, Australia, New Zealand, Mexico, the United States, and China while decreasing weight trends have been mostly limited to some Eastern European states.9,11 Much of the increased prevalence of overweight and obesity throughout the world has been noted in children and adolescents—a disturbing trend, since many overweight adolescents become obese adults.12

The prevalence of overweight and obesity in U.S. children and adolescents has tripled in the last three decades and research indicates that 15% of Americans between the ages of 6 and 19 are now obese.4,13 By comparison, in England, from 1980 through 2002, obesity in youths aged 6 to 15 increased to 16% of the population.4 Children are growing heavier at a slower rate in France, where the prevalence of overweight in 2000 was similar to that recorded in the United States in the late 1980s, and the incidence of obesity was similar to U.S. rates in the late 1970s.3

However, the numbers of overweight children may vary greatly from region to region in France and other countries as well. For example, 17% of children in Roubaix, an economically depressed industrial town in northern France, are obese. In this region, 51% of the population is overweight or obese (compared with the 2003 national average of 42%) and the prevalence of obesity is increasing most rapidly in children and adolescents.5

The average incidence of obesity in European adults is between 10% and 25% for both genders and has increased, depending on location, up to 40% over the last few decades. In England, for example, obesity in adult women rose to 23% and obesity in adult men nearly quadrupled to 22% from 1980 to 2002.14,15 By comparison, in the United States, 64% of adults aged 20 or older were classified as overweight and 30% were considered obese in 2000, a rise of more than 60% in some age groups since 1990.16,17

Quite a bit of research has been conducted to determine precisely why this worldwide increase in human girth has occurred. Clearly, no single factor is responsible; it is the prevalence and spread of a variety of “obesogenic” conditions in both developed and developing nations that lies at the root of the problem. This term consolidates the changes in food availability and type, cultural rituals and attitudes, transportation modes, community size and shape, socioeconomic status, physical activity levels, and related shifts in lifestyle and diet that promote weight gain in a given population over time. When all the real and potential factors are considered together, it becomes apparent that, just as no single factor is responsible for this problem, no single factor can “solve” it.

Too Many Calories
Surplus food energy contributes to the obesity epidemic in the United States and abroad. Since the 1970s, America’s average daily intake of calories has increased by 10%, or approximately 200 calories. Concurrently, per capita availability of sweeteners and fats increased by 20%.18 In fact, statistically, every American has access to nearly 4,000 calories per day, if all available food energy were divided evenly among us all. A large portion of these extra calories likely originates from the massive surplus of corn that has been produced in the farm belt since farm subsidy programs were changed in the late 1970s.19-21

This fact may seem confusing at first—obviously, Americans and others are not gaining weight by directly eating more corn. They may, however, be packing on the pounds by eating it indirectly, in large quantities, in the form of inexpensive sweeteners, beverages, snacks, fast foods, and meat (a large amount of corn is utilized as animal feed). Because a huge surplus of corn is produced annually, it has become an inexpensive resource that can be converted into a wide variety of foods that pack a lot of calories for a small price. Americans, though they try, cannot possibly consume all the calories available from corn and its by-products, so many calories are exported to European countries, again in the form of beverages, snacks, and fast foods.

In fact, a recent study by the World Health Organization found that increased BMI in virtually all Western European countries, Australia, the United States, and China was positively correlated with the availability of surplus calories.9 This study did not ascertain what foods provided the surplus calories, but market trends in Europe indicate significant growth in fast food and beverage markets over the same time period.22,23

An overabundance of food and calories combined with major international and domestic corporations’ desire to exhibit continued financial growth creates a barrage of campaigns designed to convince people to eat more than they physically need. Strategies to encourage people to eat more food include creating foods that are convenient to prepare and eat on-the-go, making such foods available everywhere at low costs (including schools and workplaces), advertising, increasing variety and thus encouraging the “buffet syndrome,” and providing larger portions for minimal additional cost.24 All these strategies are employed in countries around the world and they appear to be having an effect on when, why, and how much people eat.

Poverty and Energy-Dense Foods
Extra calories in the market are usually sold as energy-dense foods—ie, items packing a lot of calories into small, shelf-stable packages. The increased availability of these foods clearly promotes weight gain, especially in lower-income populations, though the reason for this may not be readily apparent.

Individuals faced with poor incomes will likely purchase foods that provide sufficient calories and satiety at a lower cost (caloric deficiencies usually occur only with overt food scarcity). Energy-dense foods are often less expensive (in dollars per calorie) than energy-dilute options and represent a large percentage of the diets of economically disadvantaged people.

Energy-dilute foods—such as fruits, vegetables, whole grains, and low-fat dairy products—typically provide more satiety with fewer calories because of their high water content.25 Energy-dense foods, on the other hand, are typically dry and are positively associated with total energy intakes of individuals and with the percent of energy in diets derived from sweeteners and fat.26 Dry foods with a stable shelf life are generally less costly, per calorie, than fresh, hydrated foods that spoil readily. Also, retail price increases over time for sweets and high-fat items are typically lower than for vegetables, fruit, and low-fat meats.18 In other words, the inverse relation between energy density and energy cost suggests that “obesity-promoting” foods are simply those that offer the most dietary energy at the lowest cost.18

Food insecurity (limited or uncertain availability of nutritionally acceptable or safe foods), low income, and minority status are associated with obesity around the world.18 In the United States, women with low incomes and minority populations (except for Asian Americans) have higher rates of obesity than white males.18 A similar pattern is seen in economically depressed areas in Europe.5 Socioeconomic status may also have a greater impact on obesity in children than adults because preferences for energy-dense foods may be formed at an early age and are usually reinforced with repeated exposure to those foods and observation of parental eating habits.27 If sweet and high-fat foods are integral to a child’s diet, as they tend to be in low-income families, preferences for those foods are likely to carry into adulthood and those adults may influence the habits of their own children.

TV Time and Physical Activity
The amount of time children spend watching TV is positively correlated with obesity. Furthermore, physical activity, which typically declines with increased TV watching time, is inversely associated with childhood weight gain. Rates of physical activity worldwide are declining while TV viewing time is on the rise. In Great Britain, up to 69% of children spend less than 1 hour per day being moderately active.28 TV viewing time in that country is inversely correlated with levels of physical activity.28 A 2000 report from New Zealand found that TV viewing was positively associated with higher BMI, lower cardiovascular fitness, increased cigarette smoking, and elevated serum cholesterol in children and adults younger than the age of 26.29 In fact, in most countries where such data are available, physical activity levels are lower and TV viewing times are higher in youths who are overweight vs. normal weight.18

Other Considerations
The prevalence of obesity in a country and community may also be linked to the variety and amounts of fruits and vegetables available to consumers, population density in urban areas, and transportation infrastructure. Availability of fresh fruits and vegetables was inversely correlated with obesity, especially in adult males, in a large study recently conducted on obesity patterns in Europe.6 Urban sprawl was positively associated with weight gain, as were poor public transportation systems. Presumably, in communities with urban sprawl, individuals are forced to drive to places of work and play instead of walking or riding a bike. Similarly, where public transportation is inadequate, people are more likely to drive to their destinations and miss out on walking to and from bus and train stations. This same study also found an inverse relationship with rates of obesity and the perceived effectiveness of government in producing sound social policies. Equally interesting was the positive relationship found between weight gain and perceived levels of government corruption. This, combined with all the other factors mentioned above, certainly makes a convincing argument for the complexity of the obesity epidemic.

Tackling the Problem
The trend for weight gain in human populations around the world seems to be due to the convergence of a perfect storm of factors. Physiologically, we are designed to crave sweets and fats; behaviorally, we tend to eat more if larger amounts and varieties of foods are presented to us; and we are literally shaped by our physical and cultural environments. Our economic status determines the types of foods available to us, and governmental policies certainly affect our lifestyles. We can’t do much to change our essential nature. As a species, we will likely always crave high-calorie foods and overeat when the opportunity presents itself.

Factors in the greater environment, however, can be changed. Better community planning, with an emphasis on health promotion, could provide physical environments that encourage fitness. Improved public transportation systems, in addition to reducing traffic congestion and pollution, would necessitate more physical activity. Policy changes in schools and workplaces that eliminate the ubiquitous availability of energy-dense foods and snacks could significantly impact the number of calories children and adults consume. (See “Local Wellness Policies — Securing a Healthy Tomorrow for Today’s Youths” [Today’s Dietitian; Vol. 8, No. 9] for more information.)

The creation of programs in schools that encourage physical activity for a lifetime (less emphasis on organized and team sports, more emphasis on individual fitness) could encourage children and adolescents to move more throughout their life. Government recognition of the far-reaching impacts of poverty and its effect on public health may help create nutrition and other assistance programs that aid individuals in the purchase of healthier foods. Increased public and governmental awareness of the widening gap between wealthy and low-income individuals could help create economies and policies that alleviate hardship.

The excess calories produced by the large corporations and immense subsidies that characterize our current agricultural system will likely continue, as will the increasing availability of energy-dense foods in the global marketplace. Public nutrition education is needed to effect behavioral change and help individuals make informed choices. Researchers are looking to the model created by tobacco cessation programs for keys to the successful promotion of population-based lifestyle changes.30 The stages of change model for counseling used in cessation programs is largely effective in that regard. However, funding for nutrition education programs certainly does not come close to that available for smoking cessation programs, and the societal changes that have helped support a large reduction in tobacco use do not currently exist for habits involving food.

Perhaps a worldwide shift in values, prompted by changes in government, school, and workplace policies, will be necessary to truly turn the tide and help create thinner, healthier people.

— Rita E. Carey, MS, RD, CDE, is a clinical dietitian and diabetes educator at Yavapai Regional Medical Center and the Pendleton Wellness Center in Prescott, Ariz.

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