Daily Protein Intake Patterns on Energy Metabolism and the Motivation to Snack

The purpose of this study is to determine if consuming 30 g of high-quality protein at each meal can increase fat utilization and shift between-meal snack choices. While the benefits of high-protein diets are well known, little is known about the optimal amount of protein that should be eaten at each meal. Most Americans eat little protein at breakfast and lunch and most of their protein at the evening meal. Current guidelines for protein are based on body weight; however, recent evidence indicates that absolute amounts of protein at each meal are needed to maintain metabolically active fat-free mass. This suggests that a more even protein consumption pattern across daily meals may positively influence energy metabolism. In addition, recent evidence indicates that protein may reduce activity in the food reward areas of the brain. This suggests that protein may influence between-meal snacking by decreasing the relative reinforcing value (RRV) of highly rewarding snack foods. The RRV of a food is an empirical measure of its motivating value and energy-dense foods are highly reinforcing, especially for obese individuals. This study will be the first to investigate the role of the daily distribution of protein intake on energy metabolism and modifying snacking behavior.

Inclusion criteria

• BMI < 25 kg/m2
• BMI ≥ 30 kg/m2 but < 34.5 kg/m2
• able to understand and sign the informed consent
• able to provide own transportation to the Center
• free of any major illness/disease
• usual protein intake within the acceptable macronutrient distribution range (10 to 30%)
• constant habitual activity patterns within the last 3 months
• females of childbearing age must be on birth control for a minimum of 3 months prior to study start and have regular menstrual cycles

Exclusion criteria

• unable or unwilling to consume animal products
• have had more than a 10% change in body weight within the past 2 months
• are participating in a weight loss diet/exercise program
• are consuming a specialized diet
• currently or planning on becoming pregnant during the study timeline
• lactating
• have a metabolic illness/disease
• have uncontrolled hypertension
• have ever had cancer
• have an infectious disease
• suffer from alcohol or drug abuse
• use tobacco and e-cigarette products on a regular basis
• have the presence of acute illness
• taking medications known to affect energy expenditure and appetite