Experts determine the type of meat that 'supercharges' muscle growth

Eating lean meat after a workout may help boost muscle growth far more effectively than fattier cuts, new research suggests.

US scientists writing in the American Journal of Clinical Nutrition studied 16 physically active adults who completed a session of resistance exercises such as leg presses and leg extensions.

After training, each participant consumed one of three post-workout meals: a lean pork burger, a high-fat pork burger, or a carbohydrate drink as a control.

Blood and muscle samples were taken before eating and again five hours later. 

After several days of recovery, 14 of the participants repeated the process to rule out individual differences.

The results showed that those who ate the lean pork burger had the largest increase in circulating amino acids – the building blocks the body uses to repair and grow new muscle tissue.

By contrast, eating the high-fat pork appeared to blunt this muscle-building response, suggesting that lean protein sources are best for recovery and strength gains after exercise.

Lead scientist, Nicholas Burd, a professor of health and body movement at the University of Illinois Urbana-Champaign called the findings 'surprising'.

On the results, he said: 'What we are finding is that not all high-quality animal foods are created equal... For some reason, the high-fat pork truly blunted the response.

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

At the beginning of the study participants received an infusion of amino acids - this allows scientists to monitor how quickly they integrate into muscle tissue. 

The blood samples collected throughout the process measured circulating levels of these amino acids.

Meanwhile, the biopsies taken before and after the infusion gave them a baseline for muscle-protein synthesis - the process of amino acids building new muscle proteins.

They discovered lean pork had a 47 per cent greater protein synthesis rate, at 0.106 per cent than high-fat pork, which was 0.072 per cent.

Professor Burd said: '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.'

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But he added 'that seems to be specific to the ground pork'.

He explained that interpreting results can be tricky as processing the pork into patties could have affected the rate and extent of nutrient digestion.

The team grounded up the pork to create patties with precisely defined levels of fat for the study.

The meat all came from the same pig, and the patties had to be sent off to a laboratory for nutrient analysis. 

Then they were frozen, to ensure the levels of nutrients stayed the same, until it was time for the participants to eat them. 

'That took us a year because it was so hard to get those fat ratios correct,' Burd said. 

He added: '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.'

While diet choices can help, he said 'most muscle response is to weight training', so they won't help you see changes alone.

The National Pork Board's Pork Checkoff program supported the research, but the funder was not involved in the study's design, data collection or analysis.