ARTICLE: Do low-calorie sweetened beverages help to control food cravings? Two experimental studies
AUTHORS: Maloney NG, Christiansen P, Harrold JA, Halford JCG, Hadman CA
SOURCE: Physiology & Behavior.2019;208(112500):1-9
SUMMARY BY: Robyn Flipse, MS, MA, RDN
This study explores whether low-calorie sweetened (LCS) beverages help regular consumers adhere to their weight loss diet goals by controlling food cravings. The authors propose the sweet taste of LCS beverages not only satisfies hedonic cravings of frequent consumers, but it may also serve as a “diet prime” that reinforces desired eating behaviors while preventing those behaviors that may result in negative feelings that could further disrupt dietary goals. Two theoretical models are cited to support the hypotheses.
The “goal conflict model” suggests restrained eaters are often unsuccessful at managing body weight because they are attempting to juggle two conflicting goals: 1. The enjoyment of eating; and 2. Weight control. Although motivated to limit their food intake to control their weight, restrained eaters often have episodes of disinhibited eating because they experience less hedonic satisfaction from what they eat when restricting themselves. The sweet taste of LCS beverages may satisfy their hedonic cravings to stay the course.
The “incentive-motivational model” suggests that people are pulled towards behaviors that lead to rewards and push away from those that might have negative consequences. For restrained eaters, repeated positive stimuli associated with a food reward, like the sweet taste of LCS beverages, may bias regular consumers of these beverages towards that stimuli and serve as a hedonic cue that keeps them from seeking other food rewards that could lead to the negative feelings of guilt associated with uncontrolled eating.
An online Food Frequency Questionnaire was used to place each of the 120 selected participants into one of two groups: 1. Frequent consumers of LCS beverages (> 825 mL/day); or 2. Non-consumers (0 mL/day). The non-consumers were also identified as consuming either >825 mL/day of sugar sweetened beverages and/or >825 mL water/day to control for volume of beverage consumption.
Frequent (N = 60) and non-consumers (N = 60) were randomized into the craving or controlled condition in a 2 x 2 between-subjects design. The craving condition was induced by having participants smell and touch their favorite chocolate candy bar for 2 minutes without tasting it. Participants were then askedto indicate how much they liked it on a visual analogue scale (VAS) ranging from “Not at all” to “Very much,” and how much they craved the bar at that moment using the same scale. The non-craving control condition involved a similar protocol but used colored wooden blocks resembling the shape and size of candy bars that participants had to smell and touch.
Energy intake after each condition was measured by providing each participant with a variety of sweet and savory snacks they indicated they liked and allowing them to eat ad libitum for 15 minutes. They were also offered a 1-liter bottle of the sugar-sweetened or LCS sweetened beverage they preferred or a 1-liter bottle of still water. All plates, bowls and beverages were covertly weighed before and after consumption to determine the amount consumed.
Attentional bias was measured using a visual probe task that involved viewing images of different beverages (LCS, SSB, and water) in different combinations, scenes and bottle varieties. Participants were instructed to press a key as quickly as possible in response to the appearance of a probe on the screen in place of the image of a beverage. Their reaction time was measured for each of the 192 timed trials.
Appetite ratings for hunger, fullness, thirst, and craving for chocolate were assessed using a VAS anchored by “Not at all” on the left and “Extremely” on the right. The impact of LCS beverages on eating-related guilt, meal enjoyment and perceived behavioral control was measured by answering specific questions related to these feelings using a VAS.
Study 1 hypothesized that energy intake would be greater in non-consumers after the craving exposure, but not in frequent consumers, and predicted that frequent consumers would have heightened attentional bias scores. Study 2 replicated the craving manipulations used in Study 1, but included frequent consumers only and controlled the availability of the LCS beverages in the ad libitum eating condition. It was hypothesized that, when LCS beverages were not available to frequent consumers, they would have increased energy intake in the craving condition and report higher guilt, lower meal enjoyment and lower perceived control.
In Study 1, frequent consumers of LCS beverages did not have increased energy intake following the craving exposure, as hypothesized, despite reporting a significant increases in chocolate craving. In contrast, non-consumers did consume more calories in the craving condition relative to the control. Frequent consumers also demonstrated an attentional bias for LCS beverages stimuli compared to sugar sweetened beverages and water stimuli while non-consumers did not show a bias. This suggests that LCS beverages are a specific stimuli to frequent consumers rather than a general bias towards sweet-tasting products.
In Study 2, the frequent consumers did eat more in the craving condition compared to the control condition regardless of whether LCS beverages were available or not. However, overall food intake was significantly higher when LCS beverages were unavailable relative to when they were available. Frequent consumers also reported lower perceived behavioral control and meal enjoyment, and higher eating-related guilt when the LCS beverages were unavailable, despite consuming more food. The reason for the conflicting findings on the ability of LCS beverages to satisfy the hedonic eating motivations of frequent consumers is not clear, so further studies in different populations are needed.
Frequent consumers of LCS beverages were not consistently protected from overeating when cravings were induced. However, they did consume fewer calories overall when LCS beverages were available during the craving manipulation. They also experienced more control over their food intake, greater meal enjoyment and less guilt. This suggests that frequent consumers view LCS beverages as hedonically desirable and their attentional bias for them indicates a specific preference rather than a general preference for sweet products. These findings provide new insight into the way LCS beverages may have a positive effect on weight control.
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Robyn Flipse, MS, MA, RDN is a registered dietitian, cultural anthropologist and scientific advisor to the Calorie Control Council, whose 30+ year career includes maintaining a busy nutrition counseling practice, teaching food and nutrition courses at the university level, and authoring 2 popular diet books and numerous articles and blogs on health and fitness. Her ability to make sense out of confusing and sometimes controversial nutrition news has made her a frequent guest on major media outlets, including CNBC, FOX News and USA Today. Her passion is communicating practical nutrition information that empowers people to make the best food decisions they can in their everyday diets.Reach her on Twitter @EverydayRD and check out her blog The Everyday RD.