It is no secret that we have been battling a major obesity epidemic in North America for the last 20 years or so. Research shows that two-thirds of Americans are overweight or obese (Ogden et al. 2014), a health condition associated with hypertension, cardiovascular disease, diabetes, depression and various cancers (breast, endometrial, colon and prostate) (Malik, Schultz & Hu 2006). Furthermore, studies find that individuals tend to gain weight slowly over time after age 50—adding approximately 1 pound per year (Mozaffarian et al. 2011). Obesity is not exclusive to North America, however. In 1995, there were an estimated 200 million obese adults worldwide and another 18 million children under the age of 5 classified as overweight. As of 2000, the number of obese adults has increased to over 300 million. Contrary to conventional wisdom, the obesity epidemic is not restricted to industrialized societies; in developing countries, it is estimated that over 115 million people suffer from obesity-related problems.
In the US, obesity-related health care costs $190 billion annually, representing five to ten percent of all medical spending. Roughly half of these costs are paid through public expenditures. The medical costs for people who are obese are dramatically higher than those of normal weight (CSPI, 2015).
With this in mind, what are the main factors that cause people to gain weight? There are six factors that predict weight gain over the North American lifespan.
Eating High-Calorie Foods
Eating behaviors associated with progressive weight gain over multiple 4-year periods included regular consumption of
- potato chips and potatoes (french fries; mashed, baked and boiled potatoes);
- red meat, processed meats (bacon, salami, sausage and luncheon meats) and unprocessed red meats (beef, hamburger, pork, lamb or game);
- butter, sweets and desserts;
refined grains (foods like white flour and white rice).
There are foods that help with weight management. Eating foods such as nuts, whole grains, fruits, vegetables, yogurt, diet (zero-calorie) soda, cheese and milk (low-fat, skim and whole) appeared to curb weight gain. These foods have slower digestion rates (some being high in fiber) and appear to enhance satiety—the feeling of being full after a meal. These foods can replace other, more highly processed foods in the diet, creating a reasonable biological mechanism whereby people who eat more fruits, nuts, vegetables and whole grains may gain less weight over time (Mozaffarian et al. 2011).
Consumption of Sugar-Sweetened Beverages
Sugar-sweetened beverages (SSBs) have little nutritional benefit and are reportedly the greatest provider of kilocalories in the American diet (Dennis, Flack & Davy 2009). In 2006, Malik, Schultz & Hu concluded that these drinks accounted for approximately 8%–9% of total energy intake in children and adults. SSBs contain carbohydrates of various forms, such as high-fructose corn syrup, sucrose and artificial sweeteners. Drinking SSBs has little impact on satisfying hunger (Malik, Schultz & Hu 2006), so people can consume large quantities without suppressing their appetite (Mattes 2006).
The body’s response to carbohydrate (of equal caloric value) differs depending on whether it is liquid or solid. In a crossover study, DiMeglio & Mattes (2000) found that people who drank SSBs gained significantly more weight than they did when consuming a comparable amount of carbohydrate in solid form. Subjects participated in both treatments, following each for 4 weeks, and the SSB treatment produced double the fat mass compared with the solid-carbohydrate intervention. Both carbohydrate sources were the caloric equivalent to three 12-ounce sodas per day in both treatments (DiMeglio & Mattes 2000).
According to extensive research compiled by the Centre for Science in the Public Interest (CSPI), an extra soft drink a day increases a child’s risk of becoming obese by about 60 percent; and adults who drink one sugar drink or more per day are 27 percent more likely to be overweight or obese than non-drinkers, regardless of income or ethnicity. In addition, people who consume sugar drinks regularly—one to two cans a day or more—have a 26 percent greater risk of developing type 2 diabetes than people who rarely consume such drinks. The risks are even greater for young adults and Asians. Furthermore, daily consumption of sugar drinks for six months increases fat deposits in the liver by 150 percent, which directly contributes to both diabetes and heart disease (CSPI, 2015)
Sleeping Too Little, or Too Much
Although more clinical trials are needed, several epidemiological studies suggest that weight gain is influenced by sleeping less than 7 hours or more than 8 hours per night (Marshall, Glozier, and Grunstein 2008). According to Marshal and colleagues, people who sleep too little develop chronically impaired glucose metabolism, steadily contributing to obesity. In addition, sleep deprivation significantly lowers circulating levels of the hormone leptin and increases circulating levels of the hormone ghrelin—both effects that promote food intake.
Altering the regulation of these hormones contributes to increased hunger and appetite, especially for carbohydrate-rich foods linked to weight gain (Van Cauter et al. 2008). Sleeping 7 to 8 hours each night contributes to a successful weight management program.
Excessive TV Watching
Length of time spent watching television is highly correlated with weight gain, especially in young people (Chapman et al. 2012). Chapman and associates tell us 58.9% of Americans watch television for more than 2 hours per day. According to these authors, epidemiologic studies reveal that those who regularly watch more daily television per day tend to
- snack more while watching;
- have higher overall caloric intake of foods; and
- consume more energy-dense foods.
All these choices lead to weight gain. Conversely, children watching less than one hour of TV a day are associated with lower body weight, body mass index, skinfold thickness and fat mass, emphasizing the importance of lifestyle in weight gain (Chapman et al. 2012).
Overconsumption of Alcohol
Alcohol is very energy-dense—at 7 kcal per gram, it is second only to fat, with 9 kcal per gram; this creates a multitude of health issues. Aside from the pharmacological effects on the brain and on hormone fluctuation, the additional kilocalories from alcohol do not seem to replace energy consumption from other sources (Yeomans 2010). Therefore, energy consumption from alcohol augments overall daily calorie intake.
Yeomans adds that alcohol consumed before or with meals tends to increase food intake, probably by enhancing the short-term rewarding effects of food. Uniquely, Yeomans cites epidemiological data suggesting that alcohol in moderation can protect against obesity, specifically in women. This means that alcohol is can be considered dose-dependent and should be monitored closely, especially while eating.
Not Engaging in Enough Physical Activity
In studying 15-year trends, scientists have noted an inverse relationship between walking and weight gain (Gorden-Larsen et al. 2009), suggesting that the more people walk, the less likely they are to gain weight. The researchers point out that older Amish people who walk an average of 18,000 (men) and 14,000 (women) steps a day have very low rates of obesity. They suggest that adding 2–4 hours of walking per week is an attainable movement target.
Despite the documented benefits of exercise, only half of Americans (51.6%) participate in the recommended volume (150 minutes per week) of moderate aerobic activity during the week, while only 29.3% do muscle-strengthening activities at least 2 days per week. Furthermore, just 20.6% of U.S. adults (23.4% men and 17.9% women) meet both the aerobic and muscle-strengthening guidelines (CDC 2011). This data can be extrapolated to Canada. This means that the majority of North Americans trying to lose or maintain weight will struggle because they are not meeting the minimum physical activity guidelines.
Exercise Specialist Recommendations:
- Watching too much TV or other screens, not getting enough sleep, drinking too much alcohol and too many sugar-sweetened beverages, eating high-calorie foods and eschewing physical inactivity indicate an obesogenic lifestyle and should be targeted in a behavior-change plan designed to prevent weight gain.
- For many people, changing one element at a time is less stressful and engenders a more successful outcome than trying to address all factors simultaneously.
- Successfully changing one factor can create cross-over success in other areas. For example, drastically reducing alcohol intake by itself can result in weight loss, making exercise more comfortable.
- Success can by stymied by an unsupportive environment. Try your best to get loved on board with your efforts, or join an online community of others who are engaged in behavioural lifestyle change.
- Weight training for a period of time (for example, 8 weeks) can build up strength and stamina, making cardiovascular exercise such as walking better tolerated.
- Do whatever you must to protect sleep. Sleep in a very dark room, go to bed at the same time each night, wear earplugs if your sleep is interrupted by a noisy bed partner, and avoid blue-lit screens (phone, ipad, computer) in the hour before bed.
- Eschew sugar-sweetened drinks at all costs, and make consumption of these a very occasional treat. If you enjoy Coke, share one can with a friend/partner a week. Sugar-sweetened drinks are deadly. Artificially-sweetened drinks are also to be avoided, as recent research shows that they impair glucose metabolism as well, and may lead to increased caloric intake from other foods.
- Know that weight management is a long- term prospect. If you are over 50, be realistic and focus your efforts on weight maintenance, instead of weight loss.
CDC (Centers for Disease Control and Prevention). 2011. Adult participation in aerobic and muscle-strenghthening physical activities--United States, 2011.
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CSPI (2015). Facts on Health Risk of Sugar Drink. https://cspinet.org/eating-healthy/foods-avoid/sugary-drinks. Retreived on July 22, 2015.
Dennis, E.A., Flack, K.D., & Davy, B.M. 2009. Beverage consumption and adult weight management: A review. Eating Behaviors, 10 (4), 237-46.
DiMeglio, D.P., & Mattes, R.D. 2000. Liquid versus solid carbohydrate: Effects on food intake and body weight. International Journal of Obesity, 24 (6), 794-800.
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World Health Organization. http://www.who.int/nutrition/topics/obesity/en/. Retrieved on July 22, 2015.
Yeomans, M.R. 2010. Alcohol, appetite and energy balance: Is alcohol intake a risk factor for obesity? Physiology & Behavior, 100, 82-89.