A new study reveals that lean pork promotes greater muscle-protein synthesis after weight training compared to high-fat pork, despite equal protein content. Researchers at the University of Illinois Urbana-Champaign found that fat in the meat blunted the body's response. The findings challenge prior assumptions about fattier foods enhancing muscle building.
The research, published in the American Journal of Clinical Nutrition, involved 16 young, physically active adults who underwent weight training sessions followed by test meals. Participants performed leg presses and leg extensions at the gym, then consumed either a high-fat pork burger, a lean pork burger, or a carbohydrate drink. Muscle biopsies were taken before and five hours after the meals to measure protein synthesis rates.
Lead researcher Nicholas Burd, a professor of health and kinesiology at the University of Illinois Urbana-Champaign, noted the surprise in the results. 'What we're finding is that not all high-quality animal protein foods are created equal,' Burd said. The team used isotope-labeled amino acids infused into participants to track how quickly they integrated into muscle tissue, with blood samples monitoring amino acid levels.
Those eating the lean pork burger showed the largest increases in blood amino acids and the highest muscle-protein synthesis rates. In contrast, the high-fat pork provided only slightly better results than the carbohydrate drink. 'For some reason, the high-fat pork truly blunted the response,' Burd explained. He suggested that grinding and processing the pork might have affected digestion kinetics, differing from previous studies where whole foods like eggs or salmon enhanced synthesis despite higher fat.
The pork patties were prepared in collaboration with the University of Illinois Meat Science Laboratory, using meat from a single pig to ensure precise fat ratios, a process that took a year. Burd emphasized that exercise remains the primary driver of muscle growth, with nutrition optimizing the response. 'Most of the muscle response is to weight-training, and we use nutrition to try to squeeze out the remaining potential,' he said. Whole, unprocessed foods appear particularly effective post-exercise.
The study was supported by the National Pork Board's Pork Checkoff program, which had no role in design or analysis.