High intakes of fructose in animals causes insulin resistance and leads to metabolic abnormalities that result in hyperlipidaemia and weight gain. Evidence also suggest that high fructose intakes are able to cause insulin resistance and weight gain in humans. Fructose is present in many fruits and has historically been present in the human diet. However, only since the widespread manufacture of refined cane sugar following the industrial revolution has fructose consumption increase substantially. In recent decades, fructose consumption has increased further through consumption of high fructose corn syrup, an artificial sweetener used by the food industry. The use of fructose compounds to sweeten soft drinks is concerning because the increase in the consumption of such products mirrors the rise in obesity seem within recent decades. That sugar sweetened drinks may be a primary cause of obesity is evidenced by studies that have caused weight loss by limiting their consumption.
For example, researchers1 have investigated the effects of replacing sugar sweetened drinks with energy free alternative on subsequent weight loss over a 6 month period. The 318 subjects were divided into three groups, two of which substituted 200 kcal of sugar sweetened drinks for water or diet alternatives, respectively. The other group were allowed to make dietary changes of their choosing, to control for the influence of research attention. The authors analysed the results using an intent-to-treat methodology, which was used to mirror the real-world clinical application of the dietary advice. Based on this principle, the results showed that a significant reduction in waist circumference, weight and systolic blood pressure was reported by the study participants in all groups. However, there were no significant differences in weight loss between the three groups (water, diet drink and attention control -2.03 %, -2.5 %, and -1.76, respectively).
Despite the lack of significance between groups, the authors did report a greater chance of achieving a 5 % weight loss at 6 months in the diet beverage group when compared to the attention controls. More importantly, a significant reduction in fasting glucose was observed in the water group compared to the attention control group at 6 months, and improvements in hydration level at 3 and 6 months were seen with water. When the diet beverage and water groups were combined, the chances of a 5 % weight loss compared to the attention control was doubled. Although energy contributed by sugar sweetened drink consumption was reduced in the treatment groups, the total energy intakes were not recorded and so it is possible that this energy was compensated for by increased consumption elsewhere. These results suggest that reductions in the intakes of sugar sweetened drinks may cause weight loss in the short-term.
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