Will reducing sugar-sweetened beverage consumption reduce obesity? Evidence supporting conjecture is strong, but evidence when testing effect is weak

Abstract

We provide arguments to the debate question and update a previous meta-analysis with recently published studies on effects of sugar-sweetened beverages (SSBs) on body weight/composition indices (BWIs). We abstracted data from randomized controlled trials examining effects of consumption of SSBs on BWIs. Six new studies met these criteria: (i) human trials, (ii) ≥ 3 weeks duration, (iii) random assignment to conditions differing only in consumption of SSBs and (iv) including a BWI outcome. Updated meta-analysis of a total of seven studies that added SSBs to persons' diets showed dose-dependent increases in weight. Updated meta-analysis of eight studies attempting to reduce SSB consumption showed an equivocal effect on BWIs in all randomized subjects. When limited to subjects overweight at baseline, meta-analysis showed a significant effect of roughly 0.25 standard deviations (more weight loss/less weight gain) relative to controls. Evidence to date is equivocal in showing that decreasing SSB consumption will reduce the prevalence of obesity. Although new evidence suggests that an effect may yet be demonstrable in some populations, the integrated effect size estimate remains very small and of equivocal statistical significance. Problems in this research area and suggestions for future research are highlighted.

Keywords: Obesity; randomized controlled trials; soft drinks; weight loss..

Figure 1

Rise in obesity rates (62) (round markers) and bottled water consumption (5) (square markers), United States. BMI = body mass index, kg/m²

Figure 2

Observed (, , –42, 63) versus theoretical (64) weight gain effect of mandatory sugar-sweetened beverage (SSB) consumption. Notes: For observed values on the Y axis, weight change was determined by the change of those drinking more SSBs minus those drinking less. The X axis was determined by multiplying the added kcal per day times the duration of the study divided by 1000. Fit lines were generated by setting the origin to zero and by using the linear regression (least squares) options in Microsoft^® Excel. The theoretical values (round markers) were generated by entering mean baseline values for each study sample into the NIDDK Body Weight Simulator (64) and adding the same number of calories per day for the same number of days as reported in the studies (, , –42, 63). Activity settings in the simulator were at the lowest level of sedentary and no activity or dietary changes over the study duration were entered into the simulator. Observed data represent an average energy compensation rate of 85% (range = 57% – 110% compensation).

Figure 3

Forest plot comparing studies of added sugar-sweetened beverage (SSB) consumption. Note: R square values were calculated from the overall standardized mean difference estimate (d) per the method found in (65).

Figure 4

Forest plot comparing studies of reduced sugar-sweetened beverage (SSB) consumption; subjects in all weight categories included. Note: R square values were calculated from the overall standardized mean difference estimate (d) per the method found in (65).

Figure 5

Forest plot comparing studies of reduced sugar sweetened beverage (SSB) consumption; only subjects overweight/obese at baseline included. Note: R square values were calculated from the overall standardized mean difference estimate (d) per the method found in (65).

Figure 6

Comparison of weight gain attributed to consumption of sugar-sweetened beverages for one year from various sources. Note: For the Haub study, the weight change shown above is adjusted by subtracting the control group weight change. * Body Mass Index of 27.8 kg/m² (NHANES 2010 50th percentile for both men and women in the United States (66) entered into NIDDK body weight simulator (64). +(67) # (68) $ (69)