Is There a Link Between Sugar Intake and Obesity? The Australian Paradox

Excess intakes of sugar and the link to obesity is a hot topic in popular media at the minute, with blame for the obesity epidemic shifting from fat consumption to sugar consumption.

It is known that any excess in kilojoule intake will result in fat storage and weight increases, but is sugar intake actually directly linked to higher rates of overweight and obesity?

The Australian national health survey showed that between the years 2014-2015 over 11.2 million Australians were either overweight or obese. That correlates to 63.4% of the Australian population. Within the age group of 5-17 years the rate was 27.4%. When broken down further the national figures show 35.5% of the population being overweight and 27.9% being obese.

A recent systematic review and meta-analysis confirmed that children who are obese are 5 times more likely of becoming obese adults than non-obese children, therefore addressing obesity in childhood is key in the fight against rising obesity rates.

Overweight and obesity are prevalent across the Australian population, however some populations and locations have noticeably higher prevalence than others. Groups with particularly high prevalence include the socioeconomically disadvantaged, Aboriginal and Torres Strait Islanders, immigrants, and those residing in rural and remote areas.

Obesity has a costly effect for the Australian economy estimated at $56.6 billion. There is also a cost to health at an individual level, with obesity being a co-morbidity for many chronic and life threatening conditions, such as cardiovascular disease and type 2 diabetes. It has been predicted that over the next decade obesity rates will continue to grow in Australia to an estimated 66% of the population, it is therefore imperative to investigate underlying causes and modifiable risk factors to help reduce the health and financial strain on the population.

There is currently a vast amount of research on the link between sugar and obesity, with a pubmed search returning a staggering 68,982 results for the search terms ‘obesity sugar’. In the USA there has been extensive research that shows a consistently positive link between sugar intake and obesity rates, however recent reviews on the subject came to opposing conclusions.

The 2014 review by Bray and Popkin concluded that consumption of sugar (in particular sugar sweetened beverages) was involved in the etiology of not only obesity but also metabolic syndrome and fatty liver disease. Kahn and Sievenpiper reviewed the same subject and came to the conclusion that there was not sufficient convincing evidence that sugar had any more impact on obesity or diabetes than any other source of calories in the diet.

The correlation between sugar intake and obesity has also failed to be confirmed when examined in other countries. Sugar consumption has significantly declined in Britain, Canada, and Australia while obesity rates have risen. The research in the Australian population has been particularly interesting and a catalyst for further research in other countries, with researchers coining the term ‘the Australian paradox’ in regards to Australia’s overall declining sugar intake and it’s soaring obesity rates.

The effect of sugar sweetened beverage (SSB) intake on obesity compared to other foods was examined by Mozaffarian et al. over a 4 year period. They used data from the Nurses’ Health Study (NHSI) (1986–2006), NHSII (1991–2003), and the Health Professionals Follow-up Study (1986–2006) for a combined cohort of a 120,877 people. They found that after adjustment for age, Body Mass Index (BMI), sleep, physical activity, alcohol, television watching and smoking, that all other dietary factors studied (intakes of French fries, potato chips, processed meat and red meats) actually resulted in more weight gain than consuming SSB.

Caution however is needed when interpreting these findings since they are based on data from cohort studies and at no point was a randomized controlled trial used to verify the findings. The cohort studies allow us to see trends and correlations but It may be possible that the foods examined in the studies are merely indicators of an overall energy dense dietary pattern whereby the overall dietary pattern is the cause of obesity and not simply an individual food that consumed that caused weight gain.

Multiple recent meta-analysis have examined a number of RCT that explored the relationship between sugar consumption and weight. Each of the meta-analysis implemented different inclusion and exclusion criteria and reported different summary endpoint estimates and conclusions. '

The isocaloric exchange of sugar or fructose with other macronutrients was examined by Sievenpiper et al. and Te Morenga et al. to assess their effect of body weight in adults. Neither of these meta-analyses showed significant effect of either sugar or fructose on body weight. With regard to sugars and weight loss Te Morenga et al. reviewed RCTs to examine whether or not reducing sugars had an effect on weight loss and found no significant difference between reducing calories from sugars and calories from other foods.

On examination of the same issue Malik et al. found 2 out of the 5 trials they examined showed significant weight loss resulting from a reduction in sugar calories when using one analysis model, but not when using another. It should be noted that in the trials that were meta-analyzed, subjects consumed not only less calories from sugar, but less total energy. Thus, it is not clear that the weight loss resulted from reduction in calories from sugar.

Within Australia much research has focused on obesity in migrant populations and in Aboriginal and remote communities. There is also a raft of research on childhood obesity and methods to prevent it. The link between sugar consumption and obesity has also been the focus of many researchers globally. The overall view is that while sugar intake can contribute to obesity by way of increasing caloric intake via discretional foods, it is the overall intake in calories, from any food source, not only sugar, which lead to obesity.

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