Dietary Carbohydrate Manipulation and Energy Balance: RCT
Condition: Physical Activity; Diet Modification
Study type: Interventional

Summary: 
      This study will investigate how dietary sugar and carbohydrates influence metabolism and
      health across a 12-week period, with a focus on physical activity. One third of participants
      will eat a diet with typical amounts of sugar and carbohydrate, one third of participants
      will eat a diet with sugar intake restricted, and the final third of participants will eat a
      diet where both sugar and total carbohydrates are restricted and replaced with fat.
    

Detailed description: 
      Sugar is perceived negatively, leading to government taxation and targets to reduce
      consumption. These actions have been taken based on the limited evidence that high-sugar
      diets are associated with greater total energy intake. However, energy intake is only one
      half of the energy balance equation (energy in vs energy out). Without considering energy
      expenditure, it is impossible to fully understand the effects of sugar on health. Removing
      dietary sugar or carbohydrates from the diet may influence energy balance through mechanisms
      other than energy intake - for example by reducing levels of physical activity.

      Understanding dietary regulators of energy balance is more important than ever because
      diseases like obesity are a consequence of energy surplus (i.e. energy in > energy out). No
      studies have investigated a causal role of dietary sugar or carbohydrate on energy balance.
      The proposed research will seek to understand the responses to manipulating dietary
      carbohydrate and sugar content on energy balance and health. This research will enable the
      public to make informed dietary choices about carbohydrate and sugar consumption.

      To achieve this, healthy non-obese adults, aged 18-65 years will be recruited to take part in
      an intervention study with measures of energy intake, energy expenditure, metabolic health,
      gut microbiota, and appetite. All laboratory trials will take place at the University of
      Bath. Participants will be randomised to consume one of three diets for a period of 12 weeks,
      with laboratory visits at baseline, at week 4, and at week 12:

        1. CONTROL (moderate sugar) - reflecting the composition of a typical European diet

        2. Low sugar - the same composition of a typical European diet but with <5% energy intake
           from sugar

        3. Low carbohydrate - low carbohydrate diet with <5% energy intake from sugar, 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: Parallel Assignment
Intervention model description: Randomised controlled trial with 3 arms. One arm is a typical diet (50% CHO, 20% SUG), one arm is low sugar (50% CHO, <5% SUG), one arm is low carbohydrate (<8% CHO, <5% SUG). Stratified by sex and physical activity level (PAL).
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Physical Activity; Nutrition; Carbohydrates; Sugar; Energy Balance