SHANON CASPERSON, PhD
Dr. Casperson received the B.S. degree in Exercise and Human Performance from the University of Houston, and the Ph.D. in Cell Biology from the University of Texas Medical School, where she studied how nutrition, specifically amino acids, and exercise independently and synergistically contribute to the maintenance of skeletal muscle mass. She joined the staff at the Grand Forks Human Nutrition Research Center as a postdoctoral research fellow in nutrition and obesity. In November 2014, she became a Research Biologist in the Center's Healthy Body Weight Research Unit.
My research focuses on the metabolic role of daily protein intake as it relates to the protein leverage hypothesis and the meal threshold concept. Most Americans consume a skewed diet, in which the majority of their total daily calories and protein intake occurs during the evening meal. In addition, approximately 9% of total calories in the American diet come from sugar-sweetened beverages. This imbalance in the macronutrient composition of the American diet may be responsible for a disruption in the homeostatic regulation of food intake and body weight. My current projects examine how protein intake distribution patterns affect energy metabolism and between-meal snacking and how the inclusion of a sugar-sweetened beverage with meals effects substrate utilization and cravings for high-sugar snack foods.
- Demonstrated that an even daily protein distribution pattern (30 g for breakfast, 30 g for lunch and 30 g for dinner) compared to skewed distribution pattern (based on NHANES data) stimulates the 24-h protein synthetic response to a greater extent (?25% greater) than a more typical pattern with a low-protein breakfast and the majority of daily protein being consumed as part of the evening meal.
- Established that increasing the leucine content of each meal enhances the anabolic stimulus of a mixed nutrient meal in older adults.
- Demonstrated that during endurance exercise: 1) amino acid exchange increases, stimulating muscle protein synthesis without an age-related resistance to the anabolic effects of exogenous amino acids, however, following an acute bout of endurance exercise the anabolic effect of exogenous amino acids is reduced in aged muscle, although this does not manifest as noticeable changes in overall net protein balance, and 2) the molecular events underlying these changes are marked by increases in the activation of proteins involved in muscle hypertrophy signaling, and decreases in muscle atrophy signaling.