Modelling study proposes reducing sugar to reduce calories
Reducing added sugars in sugar-sweetened beverages (SSBs) could significantly reduce the prevalence of obesity, according to a new modelling study.
Researchers in the U.K. calculated that a 40% reduction in SSBs' sugar content in Great Britain would lead to an average reduction in energy intake of 38.4 kcal per day (95% CI 36.3-40.7) after 5 years, which would in turn lead to an average reduction in steady-state body weight of 1.20 kg (1.12–1.28) in adults.
The prevalence of overweight adults in Britain would then be reduced by 1 percentage point, from 35.5% to 34.5%, and of obesity by 2.1 percentage points, from 27.8% to 25.7%, according to co-author Yuan Ma, a PhD student at the Queen Mary University of London, and colleagues.
The group published their findings Wednesday in Lancet Diabetes & Endocrinology.
In terms of prevention, the reduction would mean about half a million fewer British adults would become overweight and a million fewer would become obese. In addition, if the predicted reduction in body weight was achieved, there would also be 274,000 to 309,000 fewer incident cases of obesity-related type 2 diabetes over 2 decades in Britain after the weight loss.
"Individuals should also reduce their consumption of sugar-sweetened beverages in the long term, but this can be difficult because of the advertising power of industry," wrote the authors. "Our proposed strategy provides an innovative and practical way to gradually reduce energy intake from sugar-sweetened beverages and its combination with other strategies, including a tax on sugar-sweetened beverages, would produce a more powerful effect."
Tim Lobstein, PhD, of the World Obesity Federation in Australia, wrote in an accompanying editorial that the U.K. successfully reduced salt intake by using a strategy similar to the proposed one. Salty foods were identified and the government worked with manufacturers to reduce levels to a specified amount.
But he added that many assumptions were made in this modelling study, one of the biggest being that consumers wouldn't change their diets to compensate for the lower sugar intake. However, he added, "Such modelling is probably the best we can expect for the available data, and it brings a very positive message to policy makers."
The authors also calculated that if fruit juices were excluded from the category of SSBs -- because they could be harder to reformulate than soda -- the reduction in energy intake would be 31.0 kcal per day (95% CI 28.6-33.7) and 0.96 kg (95% CI 0.88-1.04) in steady-state body weight. The reductions would result in a 0.7 percentage point reduction in overweight adults and a 1.7 percentage point reduction in obesity; about 221,000 to 250,000 cases of diabetes could be prevented over 2 decades. The researchers found that the predicted effects were greatest in adolescents and those from low-income families, who consume the most SSBs.
► Note that this study examining sales data in the U.K. estimated that the prevalence of obesity could be significantly reduced if the sugar content of sugar-sweetened beverages was reduced by 40%.
► Be aware that the study is forecasting based on current estimates of consumption, which may change over time.
Combine with Taxes?
The proposal includes a reduction of 9.7% of added sugars per year for 5 years. Other proposals include a tax; according to a study in The BMJ, also released today, a 10% tax on SSBs in Mexico was linked to a 6% decline in consumption during the tax's first year.
"Tax has been very effective, and the current paper does not rule out also introducing a tax," wrote Lobstein in an email to MedPage Today. "But the current paper proposes a 40% reduction in sugar levels, introduced over five years, which is a lot more than the tax has achieved."
Ma and colleagues argued that their "proposed strategy is compatible with the tax strategy and the effect on calorie intake could be even greater if both policies are implemented together."
Data were taken from 2005 to 2013 from the British Soft Drinks Association's annual reports and from the Health Survey For England. To study the population distribution of who consumed SSBs, the researchers used data from the National Diet and Nutrition Survey, but then corrected for underconsumption, since other studies showed that self-reported intake was about 30% lower—or 41% when fruit juices were excluded—than that indicated by sales data.
The estimated annual consumption of SSBs in the U.K. increased significantly during the past decade, but it remained steady from 2010 to 2013. Nearly 90% of children ages 6-11 consumed SSBs, as did 88% of children 12-18 and 84% of those 19-25. Those in low-income households, who earned less than £5,000 ($7,300) a year, were the highest consumers of SSBs at 344 g per person per day, translating to 32 g of free sugar daily.
The average consumption of SSBs excluding fruit juice was 227 g per person per day, and 70% of consumers of such products were under the age of 25. The authors cited evidence from other studies that sugar taste preference is adjustable, and decreasing the amount of sugar slowly might not affect consumers' choices.
They also added that a reduction in energy from a reduction in sugar is unlikely to lead to higher consumption of other energy sources, and that a reduction of sugar would have little effect on the cost and price of the product so it wouldn't affect sales and profits, "meaning it could be seen as an attractive prospect politically."
They conceded that the sugar industry would likely resist. But compared with other strategies like taxation that focus on incentives, "the proposed strategy would change the environmental determinants of obesity and will benefit all consumers of sugar-sweetened soft drinks, particularly those who consume more—i.e., children, adolescents, young adults, and individuals from low-income households."
Other proposals for reducing sugar include use of artificial sweeteners, but Ma and colleagues noted that there's debate about its effect on body weight and its safety. And, they added, it could cause a taste preference for very sweet foods, leading to a worse diet.
A limitation of the study was the assumption that all groups proportionally underreported their sugary drink consumption. The authors relied on other models and studies for their analysis, so the quality of the data depended on those other studies. In addition, Ma and colleagues predicted weight change for adults only, since the model was for energy-balanced people only and not designed for children and teens.
Authors of the study and Lobstein declared they had no relevant financial interests.
Reviewed by F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner
last updated 01.07.2016
Primary Source: The Lancet Diabetes & Endocrinology
Source Reference: Ma Y, et al "Gradual reduction of sugar in soft drinks without substitution as a strategy to reduce overweight, obesity, and type 2 diabetes: a modelling study" Lancet Diab & Endocrinol 2015; DOI: 10.1016/S2213-8587(15)00477-5.
Secondary Source: The Lancet Diabetes & Endocrinology
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