Post-workout protein: Which foods really build muscle?

For people who hit the gym and want to build muscle, eating protein afterward is part of the routine. But not all protein-packed meals work the same way.

A new study has revealed that even when two meals have the same amount of protein, one might help muscles grow more than the other.

The research was focused on something pretty simple: pork burgers. Scientists wanted to know if eating a lean pork burger versus a fatty one would make a difference in how muscles grow after a workout. The answer turned out to be yes – and it’s not what they expected.

Protein isn’t just about the number

We’ve known for a while that eating protein after weightlifting helps muscles repair and grow. But this new study shows that the type of protein – and the fat that comes with it – might change how well that process functions.

The researchers worked with 16 young, active adults. Everyone took part in the same leg workout: leg presses and leg extensions. After that, each person ate either a lean pork burger, a high-fat pork burger, or a sports drink with carbs but no protein. Both pork burgers had the same amount of protein, but one had a much higher fat content.

The team used high-tech tools to track exactly how much muscle protein was being made after each meal. They took muscle samples before and after the workout and measured levels of amino acids in the blood. Amino acids are the building blocks of proteins.

Animal protein and muscle-building

Here’s where things got interesting. The lean pork burger was associated with more amino acids in the blood and more muscle-protein synthesis. That means muscles were building more protein after eating the lean burger compared to the fatty one.

“For some reason, the high-fat pork truly blunted the response,” said Nicholas Burd, a professor of health and kinesiology at the University of Illinois Urbana-Champaign.

“In fact, the people who ate the high-fat pork only had slightly better muscle-building potential than those who drank a carbohydrate sports beverage after exercise.”

The scientists were surprised, especially because earlier studies from Burd’s lab had found the opposite. Those results showed that whole eggs worked better than just egg whites, and salmon worked better than a processed version with the same nutrients.

The previous research suggested that some fat in whole foods could actually help build muscle. So why didn’t that happen with the pork? “What we’re finding is that not all high-quality animal protein foods are created equal,” noted Burd.

Lean pork and muscle protein

The research team spent a year making sure the pork burgers were carefully controlled. All the meat came from one pig, and the fat-to-lean ratios had to be just right.

After testing the meat in a lab and freezing the patties, they had participants eat the meals and tracked what happened.

“There was a little larger rise in the amino acids available from eating lean pork, so it could have been a bigger trigger for muscle-protein synthesis,” Burd said.

“But that seems to be specific to the ground pork. If you’re eating other foods, like eggs or salmon, the whole foods appear to be better despite not eliciting a large rise in blood amino acids.”

It’s possible the way the burgers were made – by mixing fatty and lean pork – changed how the body digested them. The ground pork might not behave the same way as whole cuts of meat or fish.

The best post-workout protein

The study adds to a growing list of research that shows food and exercise don’t always interact in obvious ways. Just because two meals have the same protein doesn’t mean they’ll help muscles grow the same.

“Most of the muscle response is to weight-training, and we use nutrition to try to squeeze out the remaining potential,” Burd said. “When it comes to eating after weight-training, what we’re finding is that some foods, particularly whole, unprocessed foods seem to be a better stimulus.”

So if you’re working out to build muscle, the workout itself is still the most important thing. But what you eat afterward can make a real difference – and lean protein might give you more of a boost than its fattier counterpart.

The full study was published in the journal American Journal of Clinical Nutrition.

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