Acute effects of red meat and dairy on glucose metabolism

A crossover meal study will be performed to evaluate the acute effects of red meat and dairy on glucose and insulin levels. Two isoenergetic test meals, equal in protein, carbohydrate and fat content, with one meal containing red meat and the other containing dairy products will be consumed by each participant on two separate occasions, one week apart. The red meat meal is made up of 90g beef, 59g bread, 13g butter and 250g of orange juice. The dairy meal is made up of 260g milk, 75g yoghurt, 36g cheese, 62g bread and 11g margarine. Overweight and obese adults (BMI >25) over the age of 20 will be recruited for this study. They will be separated into two groups; normal glucose tolerance and impaired glucose tolerance, as established by a 75g OGTT performed at the baseline visit, or from a previous medical diagnosis of impaired glucose tolerance. Participants will attend on three occasions following an overnight fast. The first visit is a screening visit and participants will have their fasting blood glucose concentrations determined from capillary whole blood. A 75g OGTT will be conducted, with a second glucose concentration measured 120 minutes after consumption of the drink. The glucometer readings will determine which group the participants are assigned to. Body mass will be measured by dual-energy x-ray absorptiometry (DEXA). Height will be measured at the first visit and weight at each visit. Venous blood samples will be taken at baseline, then 30, 60, 90, 120, 150 and 180 minutes after consumption of each test meal for measurement of glucose, insulin, C-peptide and triglycerides.