The Effect of High Protein Diets on Weight Loss and Lean Muscle Mass in Patients Awaiting Bariatric Surgery

This pilot project is a randomised control trial with 24 participants. Diets will consist of 1200 and 1500kcals for females and males, respectively. The control arm is to receive the Ministry of Health guidelines percentage energy from carbohydrate (50-55%), protein (10-15%) and fat (30%). The intervention arm is to be lower in carbohydrate (40%), higher in protein (30%), moderate fat (30%). Participants will be required to continue the diet for at least 8 weeks while waiting for surgery. At baseline and at eight weeks their weight, hip circumference, waist circumference, neck circumference and body composition measurements will be taken. During their prescribed diet they are required to fill out a 3-day diet record. At the end of eight weeks the participants will perform a twenty-four hour urine collect for urea and creatinine. This will help determine adherence. Post-surgery (21-28 days) they will be required to complete a surgical recovery questionnaire and the above measurements will be recorded again. These data will be collected over a period beginning January 2015. It is expected that the intervention arm will have greater weight loss and better preservation of muscle mass leading to a better surgical recovery score. However because the intervention requires a higher intake of protein this may have an effect on adherence and acceptability in these participants. There are no known adverse effects of the intervention diet in the short term.