Soft drinks alone do not affect children's weight

Soft drink consumption has increased in both the USA and the UK over the years and this has often been blamed for a rise in childhood body mass index (BMI).

However, many of the review methodologies investigating the alleged links have been flawed. A recent scientific analysis of a nationally representative sample of children's diets and lifestyles found no link between the amount of soft drinks children consume and their body weight.

UK researchers, led by Sigrid Gibson (SiG-Nurture Independent Nutrition Consultants), investigated sugars and soft drinks intake in children across the range of body weights seen in a nationally representative sample. Using diet and lifestyle data from 1294 children aged 7 – 18 years from the Government's National Diet and Nutrition Survey of Young People, the researchers showed that those with the highest BMI consumed almost 300 extra calories per day compared with children of normal body weight. However researchers determined that only 5% of this extra energy (approx 14 calories) came from soft drinks. Indeed, lighter children tended to have a higher intake of sugar (also referred to as non-milk extrinsic sugars [NMES]) overall than those in the highest BMI category.

Despite having a greater overall calorie intake (especially from fat and protein), overweight children consumed a similar amount of soft drinks to their leaner contemporaries. Importantly, the study used estimates of the subjects' energy expenditure and basal metabolic rate to screen out those who were likely to be under-reporting their intakes.

Writing in the International Journal of Food Sciences and Nutrition, Mrs Gibson stated ‘Overweight children consumed more food in general, and had a tendency towards more savoury than sweet foods.' She added, ‘we found no evidence that overweight children derived a greater proportion of their energy from caloric soft drinks compared with leaner individuals.'

Furthermore, this Survey points to a general role of overeating and physical inactivity (from both lack of exercise and excess inactivity) in obese British children. She advised, ‘In this major British survey, overweight children had significantly longer sedentary periods than children of normal weight'.

The reasons for obesity developing and continuing in children are complex, including both diet and lifestyle. The solution to obesity is also unlikely to be as simple as reducing individual food or drink products. Various untested prevention strategies have been put forward, including restricting television watching, fast foods and portion sizes. Further studies should test these strategies using reliable dietary and physical activity measurements over a reasonable period of time.