No clear mechanism has been determined for sweetened beverages causing excess weight gain. However, many have been proposed, including the lack of satiety provided by sweetened beverages leading to a positive energy balance, the adiposity-promoting effect of high fructose corn syrup (HFCS) and that sweetened beverages often replace milk which may play a role in weight control (Bachman, Baranowski, & Nicklas, 2006; Malik et al., 2006).
Researchers have found that beverages provide less satiety and there is no equivalent decrease in consumption of calories from solid food when beverages are consumed (DiMeglio & Mattes, 2000; Harrington, 2008; Mattes, 2006; Raben et al., 2002). In a classic study, a cross- over design was used to assess the difference on energy compensation between a liquid form of carbohydrates versus a solid form (jelly beans) (DiMeglio & Mattes, 2000). Authors found that liquid carbohydrate, such as sweetened beverages, do not provide satiety or compensation of energy intake over time (DiMeglio & Mattes, 2000). Experimental studies in adults have shown that energy-containing beverages did not provide satiety (St-Onge et al., 2004) and increase total energy intake, indicating no compensatory effect (Hartline-Grafton, Rose, Johnson, Rice, & Webber, 2009; Van Wymelbeke, Beridot-Therond, de La Gueronniere, & Fantino, 2004). In an intervention study on adolescents, Ebbeling and colleagues found that subjects who were
overweight and changed their sweetened beverage intake to a non-caloric beverage lost the most weight compared to those who were not in the upper tertile of BMI (Ebbeling et al., 2006). It is less clear how beverage intake affects young children’s appetite and caloric intake.
Birch and colleagues studied preschoolers’ intake of food following consumption of various beverages to determine the extent children showed caloric compensation (Birch,
McPhee, & Sullivan, 1989). Beverages included those sweetened with sucrose, low-glucose maltodextrin, and non-caloric beverages with aspartame, as well as a control of water (Birch et al., 1989). Authors found that young children do exhibit some caloric compensation, with sweetened beverages as opposed to adults (Birch et al., 1989). Researchers also noted that beverages sweetened with aspartame suppressed intake of food, and they suggest that it is due to post-ingestion cues of sweetness (Birch et al., 1989).
These findings are opposite to that of Wilson and colleagues who looked at the
compensatory effects of milk and chocolate milk at a lunch meal and found no decrease in food intake at lunch time (Wilson, 2000), nor at an afternoon snack, despite consumption of higher calorie chocolate milk at lunch time (Wilson, 1999). Similar results were found by Buyken, who found no relationship between glycemic index (GI), BMI, and increased fatness in a longitudinal study of 2-7 year olds in Germany (Buyken et al., 2008). They proposed that toddlers eat
frequently and the postprandial effects of high GI foods are not seen because preschoolers eat a snack or meal before effects of hunger are apparent (Buyken et al., 2008). It is important to note that GI, on a population level, is not only related to carbohydrate foods such as sweetened beverages, but to mixtures of foods (Schulz et al., 2005). Overall, young children may have imprecise energy regulation (Birch & Fisher, 1997; Mrdjenovic & Levitsky, 2005), and obese children may be less able to regulate energy intake (Alvina & Araya, 2004), be less responsive to internal satiety cues, and more responsive to environmental cues (Carnell & Wardle, 2009).
Some have noted that the rise in obesity has paralleled the rise in use of high-fructose corn syrup and suggested that it may play a role in this increase (Bray, 2008; Bray, 2010). High fructose corn syrup (HFCS) is a sweetener that includes fructose and glucose (Bray, Nielsen, & Popkin, 2004). HFCS-55 (55% fructose) is 1.28 times a sweet as sucrose and is commonly used in sweetened beverages (Bray et al., 2004). Fructose is absorbed differently than sucrose and does not stimulate insulin secretion or leptin production- both of which are appetite supressors (Bray et al., 2004; Elliott, Keim, Stern, Teff, & Havel, 2002; Teff et al., 2004). Studies on mice have shown an increase in weight with HFCS consumption (Jurgens et al., 2005), and studies on adults have shown a decrease in insulin response and leptin secretion, but an increase in ghrelin levels, which authors state may contribute to weight gain (Teff et al., 2004) and changes in lipid profiles (Havel, 2005; Stanhope & Havel, 2008). It is not clear how HFCS affects young
In a commentary by White (2008) it was argued that there is no significant metabolic difference between HFCS and other sweeteners such as sugar and honey. They argue that the rise in HFCS has been accompanied by a decrease in sucrose, therefore has not contributed to an increase in the total amount of sweeteners available (White, 2008). White (2008) also states that studies examining the relationship between HFCS and obesity have used inappropriate models such as very high fructose concentrations, pure fructose, or animal models that do not reflect current human consumption patterns. However, it must be noted that this author has relationships with the food and beverage industry, including corn refiners (White, 2008). Papers that have been supported by industry rarely conclude that sweetened beverages (or HFCS) are associated with an increase health risk (Lesser, Ebbeling, Goozner, Wypij, & Ludwig, 2007). Some of the authors who have received support from beverage industry include Forshee, Nicklas, and
Skinner, among others. Despite this debate, more research is needed to understand the impact of fructose-sweetened beverages on weight gain in humans (Brown, Dulloo, & Montani, 2008; Elliott et al., 2002; Havel, 2005; Stanhope et al., 2009).
It may also be that sweetened beverages replace milk intake among children, which may play a role in weight control (Bachman et al., 2006; Malik et al., 2006). Some authors have found that milk consumption among children (mean age 7.5 years) was inversely associated with age and sex adjusted BMI z-scores (Barba, Troiano, Russo, Venezia, & Siani, 2005). Others have looked at 9-10 year olds and compared their resting energy expenditure (REE) in a cross over design with either milk or fruit beverage (St-Onge, Claps, Heshka, Heymsfield, & Kosteli, 2007). Authors found that REE increased with milk supplementation over that of fruit drink supplementation (St-Onge et al., 2007). They conclude that milk has a preferential effect on metabolic energy expenditure (St-Onge et al., 2007). In a study on adults, St-Onge and
colleagues found that a mixed nutrient beverage (Boost ™) increased the thermic effect of food and increased satiety ratings, relative to a sugar-only beverage, showing a potential mechanism for weight gain in adults who drink sweetened beverages (St-Onge et al., 2004). It is unclear if this relationship would be seen in young children.