The Big Breakfast Study

This weight loss study will investigate the impact of diet composition and meal size (large breakfast meals and smaller evening meals) on body weight, energy balance and eating behaviour, by altering calorie (meal) distribution.

The aim of this study is to further strengthen our understanding of the role of dietary components (in particular fibre and protein) in a healthy diet. The information gained from this research will lead to better policy advice, particularly in relation to healthy weight management, metabolic control, mental health and intestinal health. It will also lay the foundations to produce healthier primary products and aid the food industry in developing new and healthier products (e.g. products that aid hunger control and satiety). This will be addressed through four interlinked objectives: O1: Healthy weight management and improved metabolic and mental health O2: Identification of gut bacteria and compounds of relevance to vascular and gut health O3: Linking fibre consumption to intestinal microbial communities and health O4: Mathematical modelling of interactions between diet and gut microbial communities

Phase 1: no intervention, habitual diet for 4 days and then 3day maintenance diet Phase 2: consumption of HF meals for 4 weeks Phase 3: washout for 1 week, controlled maintenance diet Phase 4: consumption of HP meals for 4 weeks

Phase 1: no intervention, habitual diet for 4 days and then 3day maintenance diet Phase 2: consumption of HP meals for 4 weeks Phase 3: washout for 1 week, controlled maintenance diet Phase 4: consumption of HF meals for 4 weeks

High fibre/carbohydrate (50% CHO, 35% fat and 15% Protein) with 45% calories at breakfast and 20% evening meal provided and buffet lunch. Total dietary fibre will be at least 30g/d for 2000kcal intake and provided as a mixed soluble and insoluble fibre sources to maintain palatability of the diet (e.g. wheat bran, fava bean, lentil, buckwheat).

• High protein diet (30% protein, 35% fat and 35% CHO) with 45% calories at breakfast and 20% evening meal provided and buffet lunch. Protein will be a mixed meat matrix to include poultry, fish, red meat, prawns, eggs, dairy. Total dietary fibre will be no more than 15g/d for 2000kcal intake.

Chronic influence on metabolism or Thermic Effect of Food (TEF) using indirect calorimetry measurement

Dual Energy X-ray Absorptiometry (DXA) Scan to measure fat mass, fat free mass & bone density as part of the 4 compartment model

Inclusion Criteria: BMI ranging from 27-42 kg/m2; those habitually consuming breakfast (at least 5 times a week). Exclusion Criteria: women who are pregnant, planning to be pregnant or breastfeeding subjects with food allergy diagnosis of diabetes, hypertension, renal, hepatic, haematological disease or coronary heart disease having given a pint of blood for transfusion purposes within the last month unsuitable veins for blood sampling inability to understand the participant information sheet inability to speak, read and understand the English language those on any prescription medications (other than oral contraceptives) those on any specific diet regimes those on any weight loss programmes (that may be affecting lifestyle, physical activity and diet).