Protein Supplementation and Fat Mass Loss

Increase intake of dietary protein has been shown to have a role in weight loss and weight management since it affects satiety, thermogenesis, energy efficiency, and body composition. However, the effects of long-term protein supplementation on body fat mass in free living individuals with overweight and obesity are not known. This knowledge is important because people are more likely to take a protein supplement and expect to achieve fat loss without any other life style modification. Our research question is, whether consumption of whey protein supplements prior to main meals will reduce body weight and body fat without other intentional behavioral changes. We hypothesize that, addition of a 30g protein drink (100% whey isolate) 1 hour before lunch and dinner would promote negative energy balance, leading to body fat reduction in free living individuals with overweight and obesity in the absence of any other lifestyle changes. Our specific aims are: (1) To determine the impact of long-term protein supplementation on energy expenditure and body composition; (2) To determine the impact of long-term protein supplementation in free living condition on satiety and hunger; and (3) To determine the impact of long-term protein supplementation on physical activity and muscle strength. To test our hypothesis, we will conduct a 12-week, two parallel group randomized controlled trial with an additional baseline week. The intervention group will be advised to consume 30g whey protein shake 1 hour before lunch and before dinner for 12 weeks while the control group will not consume protein shakes. Both groups will continue usual dietary habits and physical activity. We will measure food intake using 3-day dietary records pre-intervention, and during intervention at week 7, and 12. Physical activity will be monitored using a hip worn accelerometer pre-intervention and during 6th week of intervention. Measurements taken pre-intervention, at the end of 6th week and at the end of 12th week include body weight, body composition using dual energy x-ray absorptiometry and bioelectrical impedance analysis. Resting metabolic rate will be measured using indirect calorimetry pre- and post-intervention. Between-meal satiety and hunger will be measured using 100 mm Visual Analog Scales at 6am, 11am, I hour after lunch, 6pm, 1 hour after dinner at baseline, day 14th, 43th and 83rd.