DESIGN Randomized, cross-over design with two 7-day dietary interventions separated by a 4 week wash-out period. Dietary intervention will be based on iso-energetic substitution of sucrose for starch in a weight-maintaining diet. The two experimental conditions are: high sucrose diet at 25% of total energy intake (this is approximately the 95th percentile for UK intake of non-milk extrinsic sugars (NMES)); and low sucrose diet at 10% of total energy intake. Otherwise the macronutrient balance in both conditions will be based on UK average habitual intake.