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What does protein do?
Protein is one of the 4 macronutrients that once digested, is broken down into subunits called amino acids.
Protein has a structural role – for example, to make cells, tissues, muscles and bones. And a functional role – enabling all of the different processes and reactions to take place in the body, for example muscular contraction.
Enough protein is critical general health and wellbeing– from bone health, to cognitive health to immune health (1).
Some examples of what protein does:
Daily protein intake
Although the recommended daily allowance (RDA) is 0.8 g/kg/day (2), this is considered necessary to prevent being deficient. However, having sufficient protein intake may not be the same as optimal intake – more and more research suggests that a greater intake is beneficial.
If you are active, a dietary protein intake of 1.2-2.2 g/kg/day is recommended to support needs – such as muscle repair and recovery (3). Requirements vary depending on the individual.
Guidelines (g/kg protein/bodyweight):
Benefits of protein
Build muscle: amino acids are necessary to build muscle mass gains (10, 11, 12)! Without hitting your daily protein intake, you will not have the building blocks to gain. Sure, you need to train, but if you don’t have sufficient circulating levels of amino acids, you won’t be able to build the muscle.
Whilst resistance training upregulates specific factors involved in muscle growth (mTOR) (13), having enough protein distributed throughout the day, enhances this factor (mTOR) (14).
If you’re looking to up your muscle mass, resistance training + hitting daily protein intake is a must!
Better fat loss: fat loss means you retain lean muscle mass whilst losing bodyweight – therefore protein intake is key. A higher protein intake during a calorie deficit results in a greater proportion of weight loss being fat loss than a lower protein intake (15).
Increasing protein intake to approximately 35% of macronutrient intake vs 15% is superior for fat loss (16).
Better strength and performance: sufficient daily protein intake and distribution is associated with better strength and performance (10,11,12). Performance benefits are seen for anaerobic power and strength for resistance trained individuals who take a protein supplement (17).
Protein supplementation is also associated with significant improvements in performance for endurance athletes(19). Intense or prolonged bouts of endurance exercise uses considerable amounts of amino acids, specifically leucine and therefore protein supplementation, with a focus on leucine may be beneficial. Consuming a form of branched chain amino acid (BCAA) in specific, during endurance exercise has been shown to improve performance (20) and delay central fatigue (21).
Weight managament: protein is the most satiating macronutrient – eating a higher proportion of protein within the diet results in less hunger and greater fullness (31,32). Consuming protein increases levels of the fullness substance – GLP-1 and PYY.
Protein is the macronutrient with the highest thermic effect, which means that it costs the most energy to be digested and absorbed. If you’re looking to expend more energy whilst keeping calorie intake the same, simply increase the relative proportion of protein (decreasing the others)! Unlike increasing calories from the other macros, increasing calories from protein may increase overall energy expenditure (29).
Better recovery: training requires energy and involves the breakdown of muscle fibres – adequate energy and protein intake is critical for the body to adapt from training to become stronger (1). Whilst carbs and fats provide energy, protein provides the building blocks (and energy if need be) necessary to rebuild those muscle fibres, repair damaged muscle tissue and build new lean tissue! Ensuring adequate protein intake, along with overall calorie determines an athlete’s recovery.
Higher protein requirements are also recommended for individuals with any injury – in order to rebuild the lost or damaged tissue (27). A diet high in protein and rich in micronutrients promotes wound healing (28) and consuming BCAA may improve markers of immune health (20).
Should I take a protein supplement?
Meeting your daily protein intake, followed by distributing it relatively evenly throughout the day are your priorities! Check out Does protein distribution matter for maximising your muscle gains for more info on this.
Although it has been shown that post total-body resistance training, consumption of a protein supplement results in lower rates of whole body protein breakdown (17), overall research indicates that if you are meeting your daily needs and distributing your protein throughout the day, it’s unlikely that a protein supplement will take your muscle gains any further!
If you are training a fair amount, then check out Nutrient timing – what’s the deal and does it matter when you eat. Consuming a protein supplement may be beneficial in preventing decreases in muscle performance and improving delayed onset of muscle soreness (22,23). Marathon runners receiving protein supplements show significantly lower biomarkers of damage and stress than those who didn’t receive protein supplementation (24).
If you train a lot and are on a lower carb diet /keto, protein supplementation post training may be more valuable in the recovery process, improving glycogen replenishment and decreasing symptoms of muscular damage (25). Additionally, taking a protein based drink post work out assists with the rehydration process (26) a critical component of the recovery process.
Protein is a macronutrient with diverse roles: integral to general health, well-being, performance and recovery. It’s necessary for everything – from bone, cognitive and immune health, to the maintenance, building, recovery and repair of muscle tissue.
Adapt your protein intake depending on your individual needs: and shoot for what is optimal for you. If you exercise regularly, are trying to lose weight or gain muscle, are recovering from an injury, or are older, adapt your needs accordingly.
Hitting your daily protein intake has many benefits including: better fat loss and muscle mass gains, easier weight management through reduced hunger and improved strength, performance and recovery.