How much protein do I need after a workout?

For a long time, it was believed that you needed no more than ~20g of whey protein post-training. But why? And is this still the case?

Studies examining how much (and what type of) protein we should take post-training come from studies that  measure how much ‘new’ protein we are able to make in our muscles after training (skeletal muscle synthesis) - this is the whole point of training. Earlier studies showed that there was no added benefit for muscle growth beyond 20g of protein - even if you doubled the intake to 40g (1). This did spawn one myth that should be put to bed.

It is a myth that your body can’t handle any more than 20g of protein in one go. This needs to be put straight into the bin and never return.

If you consume more than 20g of protein in one sitting, it is just used for other processes within the body. It might go to a vital organ, it can be used for energy production - it is not just wasted. It also helped reduce any hunger you might have felt after a workout.

A New Protein Ceiling

The original work though showing that there is no added benefit for muscle growth beyond 20g protein stuck for a long time though. That was until two recent studies.

The first study again looked at 20g vs 40g. But, unlike the original study that used a leg only training session, this new study used a whole body resistance training session (2). Their theory was that, as we were using more muscle mass, we would most likely need more protein afterwards. What did they find? A 20% increase in skeletal muscle synthesis when participants took on 40g vs 20g.

So, it appears that how much protein you consume after training or competition might depend on how hard the session was and how much of the body was used. Full body session? You might need up to 40g of protein. Upper or lower body only, you maybe only need around 20g.

If we use a greater proportion of our muscle mass during a training session, we probably need more protein.

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Training Into Old Age - More Of The Same?

Another recent study has even shown that 40g may also be more beneficial post-training as we age. As we age, our response to exercise training appears to diminish and is one of the reasons for drop offs in muscle strength and function of up to 60% in over 70 year olds compared to younger adults.

In this new study, unlike the study in younger adults that measured protein synthesis after a single training study - this study in older adults wanted to look at the practical effects of consuming either 20g or 40g post training (3). Both groups completed 10 weeks of training, completing 3 training sessions per week. All sessions were supervised and the participants completed a range of resistance exercises to hit the major muscle groups. At the end of the 10 weeks, both groups retested their 1RM to see if there had been any improvement. Those in the group consuming 40g post-training showed significantly improved strength performance in chest, shoulder and leg press compared to a matched group that only consumed 20g. Same training - but better results. 

The low down on protein doses:

  • 20g of protein is probably enough when your performing split body workouts (only upper body or only lower body)
  • If you are training your whole body, this probably needs to go up closer to 40g
  • If you have a greater overall muscle mass, both of these values are likely be higher - more muscle mass = more protein needed.
  • Older adults appear to have greater training gains when they consume more protein post training.


1 - Moore, D. R., Robinson, M. J., Fry, J. L., Tang, J. E., Glover, E. I., Wilkinson, S. B., ... & Phillips, S. M. (2009). Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. The American journal of clinical nutrition89(1), 161-168.

 2 - Macnaughton, L. S., Wardle, S. L., Witard, O. C., McGlory, C., Hamilton, D. L., Jeromson, S., ... & Tipton, K. D. (2016). The response of muscle protein synthesis following whole‐body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiological reports4(15).

3 - Atherton, C., McNaughton, L. R., Close, G. L., & Sparks, A. (2020). Post-exercise provision of 40 g of protein during whole body resistance training further augments strength adaptations in elderly males. Research in Sports Medicine28(4), 469-483..