What is the maximum amount of protein my body can use at a time and when is the best time for me
Here’s a quick background and summary of the facts to date:
Amino acids are the building blocks of protein.
Protein can be used to repair/build muscles or broken down for energy.
Excess protein not used for energy like other macronutrients (carbohydrates and fat) is stored as fat.
Leucine (an amino acid) is mostly responsible for stimulating protein synthesis which is naturally high in whey protein, milk (contains whey protein) and meats.
2-3g of leucine, found in 20-30g protein, provides the maximum stimulation for protein synthesis.
Protein synthesis rate is highest up to 3 hours pre/post workouts.
So ideally for muscle building you should have 20-30g protein 3 hours before and after workouts.
I attached a table below on sources of 2g leucine from the Sports Dietitians Australia Fact Sheet and amount of protein required per kg body weight from the Australian Institute of Sport Current Concepts in Sports Nutrition.
Cribb PJ, Hayes A. Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy. Med Sci Sports Exerc. 2006;38(11):1918-25.