Lean pork stimulates more muscle protein synthesis after exercise than high-fat pork, despite equal protein content Digest
After exercise, many people reach for a protein-rich meal to help muscles recover and grow. But foods with the same protein amount do not always trigger the same muscle-building effect. A new study from the University of Illinois tested whether the amount of fat in pork affects how the body uses the food's protein to rebuild muscle after strength training.
Sixteen healthy, active adults (12 men and 4 women, average age 25) completed two experimental trials, each consisting of a resistance exercise session followed by one of three post-workout meals: a lean ground-pork patty (20 grams of protein, 4.4 grams of fat), a high-fat ground-pork patty (20 grams of protein, 20.6 grams of fat), or a carbohydrate drink matched in calories to the high-fat pork patty, but containing no protein or fat. Over the next five hours, researchers took blood samples and small muscle biopsies to track amino acid levels and how quickly muscle proteins were being rebuilt after exercise.
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Here's what they found:
- Lean pork was linked to the greatest rise in muscle protein synthesis after resistance training, a roughly 120 percent increase.
- The high-fat pork meal also stimulated synthesis, by about 64 percent, but this smaller gain was statistically similar to the carbohydrate condition, which showed only a non-significant 40 percent rise from baseline.
- The lean pork meal produced a higher peak in essential amino acids and a higher, earlier peak in leucine, a key amino acid that helps trigger muscle repair and growth. These differences were moderately correlated with the size of the muscle-building response.
Because fat slows stomach emptying, the higher-fat meal likely delayed how quickly amino acids entered the bloodstream. In contrast, the lean pork meal produced a more favorable post-exercise amino-acid profile. The researchers also examined whether the meals altered cellular signaling within the Akt–mTOR pathway, a key regulator of muscle protein synthesis and growth. Overall, the signaling markers showed mixed responses that did not align with the observed differences in muscle protein synthesis. This suggests that the timing and pattern of amino acid delivery, rather than stronger activation of growth signals inside the muscle, were the main drivers of the greater response to the lean pork meal.
The study results suggest that leaner meat sources may help muscles rebuild more effectively than fattier versions with the same amount of protein. However, this study tested only pork-based meals in young, healthy adults, so further research is needed to determine whether similar effects occur with other foods or in different populations. Learn more about optimizing protein intake in episode #93, featuring Dr. Luc van Loon.