Muscle is dynamic: every day we breakdown 1–2% of our muscle and rebuild it to better adapt to our environment. While exercise increases the rate of protein breakdown, it also increases the rate that is synthesised in the recovery period. Combining this exercise-induced rise with dietary protein results in an additive effect on muscle protein synthesis. But how much protein do we need to max our muscles?
With everyone talking about high-protein diets, you’d be forgiven for thinking that more is better – particularly at the expense of carbohydrate. The truth is that consuming protein above requirement will not further increase muscle mass. Any excess amino acids are disassembled in the liver and the nitrogen is excreted and the carbon skeletons are oxidised for energy or stored as fat.
So what is our requirement?
Women aged 19–70 years require 0.75g protein per kilo of body weight, which means a 65kg woman would need nearly 50g protein per day. Men of the same age require 0.84g protein per kilo of body weight, which is roughly 67g protein if you’re an 80kg man. These intake levels are easy to achieve, and most Australians exceed their protein requirements. Strength athletes such as weightlifters and sprinters may need double that of sedentary folk to repair damaged tissues and support muscle protein synthesis.
But what matters most when it comes to building muscle is not our total daily protein intake but, more specifically, the quality, the dose and the timing of our protein intake.
The protein digestibility-corrected amino acid score is commonly used to rate protein quality. Foods with the highest scores are milk, eggs and soy protein.
The dose required for maximum results is 20–25g protein including 3g of the branched-chain amino acid leucine. This can be obtained from a variety of sources: 600ml skim milk, 350g skim natural yoghurt, 70g reduced-fat cheddar, 140g cottage cheese, 3 eggs or 120g meat or seafood. If you’re vegan, you can get 3g leucine from 400g tofu, 900ml soymilk or 350–380g of kidney beans or lentils.
Consuming protein immediately after exercise markedly increases the rate of muscle protein synthesis. A study found that pre-exercise protein intake and resistance exercise can achieve a 60% increase in muscle protein synthesis whereas protein ingestion after resistance exercise can boost the rate to 140%, so there is a significant difference with nutrient timing. Post-exercise feeding is seen as the ‘window of anabolic opportunity’ as it is the most responsive time for muscle building. The window might be open for 24–48 hours after resistance exercise, but the most intense response to nutrition is within the first hour after exercise so you’ll get maximum results by eating immediately after training.
For the rest of the day, try to distribute your protein evenly so that each meal contains a moderate amount of high-quality protein rather than having too little at breakfast and lunch and a large serving at dinner. A recent study demonstrated that evenly distributed protein consumption can increase muscle protein synthesis by 25% when compared to protein that is skewed toward a single meal.
Putting it all together
Straight after your resistance training session, try one of the following:
- Top your morning oats with nuts, seeds and berries and add half a cup of skim milk and 200g low-fat Greek yoghurt. Enjoy with a latte – soy or cow’s milk
- Blend 1 cup skim milk, 200g low-fat Greek yoghurt, 1 cup of kale, a squeeze of lemon juice and a banana for a tasty green smoothie
- Make a spinach, asparagus and cheese omelette
- Stirfry a few cups of vegetables with 120g salmon.
These meals all provide the right amount and type of protein to ensure maximum muscles. They also include carbohydrate, which increases insulin production. Insulin helps prevent exercise-induced muscle protein breakdown, which means that you’re building muscle but you’re also maintaining the muscle you already have.
 Drummond MJ, Dreyer HC, Fry CS, Glynn EL and Rasmussen BB. Nutritional and contractile regulation of human skeletal muscle protein synthesis and mTORC1 signaling. J Appl Physiol 2009;106:1374-1384.
 Mamerow M, Mettler JA, English KL, Casperson SL, Arentson-Lantz E, Sheffield-Moore M et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. Jun 2014; 144(6): 876–880.