Science reveals what makes people put on pounds over the long term.
Fitness professionals expend considerable energy helping people to lose weight, but there’s another way to view this challenge: What are the main factors that cause people to gain weight?
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 Americans tend to gain weight slowly over time after age 50—adding approximately 1 pound per year (Mozaffarian et al. 2011).
Understanding the specific behaviors that increase the risk of weight gain is essential to helping clients manage their weight. While most weight management articles focus on strategies and behaviors for losing weight, we will examine the other side of the coin: six factors that predict weight gain over the American lifespan.
1. Eating High-Calorie Foods
Mozaffarian et al. (2011) found that 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; and
- refined grains (foods like white flour and white rice).
Foods That Help With Weight Management. Studies also found that 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. Mozaffarian et al. (2011) explain that 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).
2. Consuming 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).
3. 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 (see Figure 1) (Marshall, Glozier
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 (Van Cauter et al. 2008).
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). Ideally, sleeping 7–8 hours each night complements a successful weight management program.
4. Watching a Lot of TV
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.
Other evidence indicates that visual images of palatable food (as regularly seen in food commercials) evoke increases in plasma ghrelin concentrations, thus boosting the hunger/eating response (Chapman et al. 2012). Conversely, children watching less than 1 hour of TV a day are associated with lower body weight, body mass index, skinfold thickness and fat mass. These children are also less likely to be overweight, emphasizing the importance of lifestyle in weight gain (Chapman et al. 2012).
5. Overconsuming 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 somewhat dose-dependent and should be monitored closely, especially while eating.
6. Not Engaging in Enough Physical Activity
It’s our business to know this, but there’s no harm in reviewing the science. 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. Gorden-Larsen et al. (2009) 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. (CDC 2011). 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 means that the majority of Americans trying to lose or maintain weight will have a positive weight balance because they are not meeting the minimum physical activity guidelines.
Weight Gain Solutions
Watching too much TV, not getting enough sleep, drinking too much alcohol and too many sugar-sweetened beverages, eating high-calorie foods and eschewing physical inactivity are clear indicators of an “obesogenic” lifestyle and should be the targets of any behavior-change plan designed to prevent weight gain (see Figure 2). Psychological stress accompanying these behaviors may exacerbate weight gain, so exercise professionals have to factor that into their interventions (Montes
Kravitz 2011). Personal trainers may be best advised to expand their training efforts to address all of these areas with clients, to ensure successful weight management goals.