Primary researchers: Nouf Gadah, Peter Rogers (PI)

Collaborators:Jeff Brunstrom, Lesley Kyle

External collaborators: Jessica Smith (University of Oxford)

There is currently much debate about the role of added sugar in our diet in relation to weight gain and obesity. In particular, sugar-containing drinks are thought to be particularly problematic, with some claims that ‘liquid calories’ are not sensed by the appetite control system.

Research findings spanning over 3 decades shows this is not the case – these studies have used a procedure in which participants consume a drink containing sugar, or a control drink (water, or a drink sweetened with a low-energy sweetener), and subsequently eat a meal in which their food intake is measured covertly. This ‘preload, test-meal procedure’ has shown that consuming sugar in a drink does suppress appetite, but not sufficiently to fully ‘compensate’ for the calories in that drink.

Our recent research has tackled some technical issues with these methods, and found that the degree of compensation may be higher than previously thought. This is important because these methods are used widely to test new food ingredients and formulations to aid appetite control, and it suggests that the effects of sugar in encouraging overeating may have been overestimated.

Nonetheless, this research, and a recent work we have done reviewing the literature on low energy sweeteners and weight control, does show that high sugar intake is likely to contribute to weight gain. The same is true for other dietary choices, in particular where these lead to increasing the energy density of our diet.

Our research has compared the effects of sucrose versus low-calorie sweetener (sucralose) in a drink preload on test-meal energy intake. The parallel-groups study included a baseline day in which only the test meal was consumed. The effect of consuming sucrose on subsequent energy intake was greater when measured in the parallel-groups study than in the cross-over study. We also found that test-meal energy intake did not differ significantly between the water and sucralose conditions. Together, these results confirm that consumption of sucrose in a drink reduces subsequent energy intake, but by less than the energy content of the drink, whilst drink sweetness does not increase food energy intake. Crucially, though, the studies demonstrate that study design affects estimated energy compensation

• Gadah, N. S., Brunstrom, J. M., & Rogers, P. J. (2016). Cross-over studies underestimate energy compensation: The example of sucrose-versus sucralose-containing drinks. Appetite, 107, 398-405. Click here to read.
• Rogers, P. J., Gadah, N. S., Kyle, L. A. & Brunstrom, J. M. (2011) Standard preload-test meal designs may underestimate satiety effects: sugar containing drinks as an example. Proceedings of the Nutrition Society, 70 (OCE6), E401.

Our research on this topic has been funded in part by Sugar Nutrition UK

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