Acute Responses to Manipulating Dietary Carbohydrate Content on Free-living Physical Activity Energy Expenditure
Condition: Physical Activity
Study type: Interventional

Summary: 
      Dietary sugar and carbohydrate intakes will be manipulated for 3 days in a randomised
      crossover design. All food will be provided. Free-living physical activity energy expenditure
      will be measured using combined heart rate and accelerometry. Metabolic and appetite/mood
      responses to 3 days on each diet will be measured.

      Each participant will undergo 3 days of each diet:

        1. Moderate sugar - reflecting the composition of a typical European diet

        2. Low sugar - similar macronutrient composition of a typical European diet but with <5%
           energy intake from free sugars (as per government guidelines)

        3. Low carbohydrate - low carbohydrate diet with <5% energy intake from sugar and <8%
           energy intake from carbohydrate, replacing carbohydrate energy with fat
    

Detailed description: 
      Guidelines calling for dietary free sugars to be reduced have been formulated from evidence
      that diets high in sugar are associated with high energy intake. In theory, by reducing the
      intake of sugars, calorie surplus will be reduced and energy balance will be maintained.
      However, when referring to interventions/behaviours that influence energy balance, both sides
      of the energy balance equation need to be considered. Alterations in nutrients may influence
      aspects of energy expenditure, not solely energy intake, and this may have implications for
      the efficacy of guidelines seeking to influence energy intake.

      It is important to consider energy expenditure in the context of health. The most variable
      component of energy expenditure between individuals is physical activity energy expenditure
      (PAEE), which varies from ~600-2100 kcal per day in men of a similar demographic. Current
      guidelines do not regard the effect that changing dietary sugar might have on PAEE and
      therefore total energy expenditure.

      Furthermore, there is increasing interest in restricting overall carbohydrate intake to treat
      metabolic disease or achieve ketogenesis. Very little is known about nutrition-physical
      activity interactions with this type of intervention.

      This study will prescribe 3 diets to healthy males for 3 days in a randomised crossover
      design, where each participant will consume each of the diets. All food will be prepared and
      provided by the study team. The diets are as follows:

        1. Moderate sugar - reflecting the composition of a typical European diet

        2. Low sugar - similar macronutrient composition of a typical European diet but with <5%
           energy intake from free sugars (as per government guidelines)

        3. Low carbohydrate - low carbohydrate diet with <5% energy intake from sugar and <8%
           energy intake from carbohydrate, replacing carbohydrate energy with fat
    

Intervention name(s): Diet
Intervention type(s): Other
Intervention description(s): Macronutrient composition (specifically type and/or amount of carbohydrate) is manipulated
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Randomised crossover design
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Nutrition; Carbohydrates; Ketogenic; Metabolism