Table 5 Considerations for future studies related to the top three high priority research questions

High Priority Research Question 1.

 What is the long-term (>1 year) effect of a reduction in the intake of sugars on body weight or body composition in overweight or obese adults and children

 Both long-term RCTs and large prospective cohorts on all population groups are needed to address this evidence gap. It is important to note that studies of weight loss need to isolate the effects of reduction in sugars intake from the effects of total energy reduction. Also, the macronutrient proportion in a diet and physical activity levels need to be examined concurrently in future studies addressing the long-term effect(s) of a reduction in sugars intake on body weight or body composition.

High Priority Research Question 2.

 Do dietary sugars have a different impact on body fat deposition than other macronutrients?

 Both controlled human metabolic studies and basic science studies are needed to investigate this research question. The overall energy balance of the study design is important because iso- and hyper-caloric intake may have different metabolic effects. The metabolic difference between iso- and hyper-caloric conditions is also in need of investigation. Moreover, the energy balance of any comparison group is an important design consideration in RCTs focused on teasing out effects of different types or sources of sugars on body composition while holding total energy constant. Overall study design is important in examining whether sugars or other macronutrients cause different patterns of fat deposition.

High Priority Research Question 3.

 What is the effect of sugars intake on satiety and hunger mechanisms?

 Does sugars intake affect leptin and ghrelin levels, appetite, or fullness?

 What are the different effects on satiety and appetite between different types of sugars (fructose, sucrose, high fructose corn syrup, honey, added sugar vs. intrinsic)?

 A systematic evidence review of all published human studies on this topic is needed. Based on the evidence-mapping data, existing studies have generated highly variable outcomes, depending on the methodology used. An expert panel specifically on satiety and hunger mechanisms is needed to assist in the interpretations of the evidence base in order to identify existing methodological issues and to inform future research designs. Controlled, experimental studies to develop better measurement tools or to define reference biomarkers for measuring satiety, hunger and appetite are of higher priority than large scale population-based studies.