The Recommended Dietary Allowance (RDA) for protein is currently set at 0.8g per KG of body weight per day. However, it’s important to remember that the RDA is the quantity required to prevent deficiency, and NOT to optimise muscle protein synthesis (MPS). Before calculating how much protein you need, it’s important to first identify what your goal is. Whether that be to reduce body fat, build muscle or just prevent a deficiency, your target intake should be adjusted accordingly.
Protein is a macronutrient made up of amino acids, often referred to as the ‘building blocks’ of muscle. In total, there are 20 amino acids, 9 of which are essential (EAA), meaning that they must be consumed the diet as the human body is unable to synthesise them itself. Of these 9 Essential Amino Acids, 3 are Branched Chain Amino Acids, a very popular training supplement with aim of reducing muscle breakdown (whether they work will be discussed another time!).
The following are Essential Amino Acids:
In terms of building muscle, studies have shown leucine to be by far the most significant amino acid. In sufficient quantities, leucine triggers a signalling pathway called mTOR, and subsequently the protein kinase p70S6K, leading to the activation of MPS. Research suggests the required intake of leucine to activate MPS is between 2-3g. Any less than this and it doesn’t quite reach the threshold, any more and no greater degree of activation occurs.
So How Much Do You Need?
Your requirements are not only specific to your goals, but also your bodyweight. If your goal is to reduce body fat, then consuming higher amounts of protein has been shown to be beneficial. Firstly, in order to lose body fat, you must be in hypocaloric state in which you are consuming fewer calories than you need for maintenance. In this calorie deficit, your body must get energy from somewhere, this puts your muscles at a greater risk of being catabolised and used as ATP (energy). By supplying the body with a greater quantity of amino acids, MPS can occur and the muscle tissue is far better protected.
In addition to this, it has been suggested that protein increases satiety and make us feel fuller for longer. When attempting to lose body fat, the most common problem that seems to occur is failure to overcome hunger. With the additional protein, you might find yourself feeling more satiated and therefore less likely to put your hand in the snack drawer!
If your goal is to either maintain or build muscle in a calorie surplus, then surprisingly to some, less protein is required. When in a hypercaloric state, the macronutrients carbohydrates and fats will often cater to our energy requirements, leaving protein to its own devices so it can focus on building muscle!
Requirements for fat loss:
1.8-2.5g / kg bodyweight / day
Requirements for maintenance & building muscle:
1.4-1.6g / kg bodyweight / day
When deciding which number to aim for, consider your physical activity levels, but also food preferences. If you enjoy eating protein, whether that’s chicken breast, whey protein or soy, don’t be afraid to opt for a higher intake. Similarly, if you would rather consume more carbohydrates and fats, aim for the lower range to make room in your calorie budget for them.
Phillips, S. and Van Loon, L. (2011). Dietary protein for athletes: From requirements to optimum adaptation. Journal of Sports Sciences, 29(sup1), pp.S29-S38.