Historically this would have meant being smaller or thinner but now it is just as likely, particularly in men, to mean a desire to bulk up, build muscle and increase lean mass.
Muscle fibers are made from protein and gym myths often directly link protein intake with muscle size. But to build muscle you need three things, to work the muscle, to eat a diet containing enough energy and the right balance of nutrients and sufficient sleep.
In adults approximately 16% of total body weight is protein. 43% of this is in muscle, 15% skin and 16% blood. Enzymes, hormones, neurotransmitters and many other key elements of the body are also protein based. All protein in the body is in a constant state of flux – all protein structures are constantly being broken down and rebuilt and require a constant supply of new amino acids, as these are not stored if not used.
The recommended daily intakes of protein in the UK varies with age and are shown in the table below taken from the 2016 Public Health England’s Government Dietary Recommendations (1). These numbers are approximations built on a recommended intake of 0.75g-1g/Kg bodyweight/day in adults and slightly more in children, adolescence and old age. These numbers will be slightly higher in individuals who are in regular training, as is covered in Future Fit’s Nutrition for Exercise courses but there is also such a thing as too much protein, with high intakes having some quite serious side effects. Adult studies have shown that the maximum safe intake is between 2 and 2.5 g/kg of body weight per day (25% intake). Intakes greater than this level may stress kidney and liver function, cause leaching of calcium from bones, kidney stones and fatigue (2).
However, there is a way to optimise protein assimilation and help build muscle without increasing protein intakes wildly, as the latest research in the area is showing that the timing of protein intake maybe the key.
The first benefit is to consider splitting out intake evenly between meals. Analysis of diets in the UK generally shows that the bulk of daily protein intake is in the evening, as part of the larger evening meal. Better protein distribution has been shown to increase useful intake, slow breakdown, increase muscle building and promote repair. Splitting protein intake into 3-5 evenly sized meals of ~20g has been shown to improve assimilation and also slow muscle wasting in the elderly (3).
The second tactic is to take advantage of the increase in muscle protein synthesis rates that occur after exercise. Multiple studies have shown that eating a high quality protein source within a 1-3hr window after exercise can increase aggregation. Other studies have found that taking protein before or during exercise is also of benefit. However all these studies have also shown that protein alone is not the best solution and that optimal recovery and nutrient assimilation is achieved if carbohydrates and proteins are combined (4). Chocolate milk is often promoted as the perfect post-exercise drink with a protein carbohydrate ratio of 1:4 (5)
My last tip would be to take a glass of milk or high protein snack to bed, as research has also shown there is an increase in muscle assimilation during sleep (6).
So it is not always the best solution to take more and more protein without thinking first about improving the way in which you take it. Studies done with academy footballers have shown that simply changing the distribution of nutrients with in the diet and during the day has resulted in considerable beneficial performance gains.
|AGE IN YEARS||PROTEIN REQUIREMENT g/day|
|15-18||MALE 55.2g FEMALE 45.0g|
|19-64||MALE 55.5g FEMALE 45.0g|
|65-74||MALE 53.3g FEMALE 46.5g|
|75+||MALE 53.3g FEMALE 46.5g|
To learn more about protein in our Nutrition & Weight Management course.
(2) Bilsborough and Mann (2006) Review of issues of dietary protein intake in humans. Int J Sports Nutr Exercise Metab 16(2), 129-52
(3) Courtney-Martin et al (2016) Protein Requirements during Aging. Nutrients 11(8) 3390.
(4) Van Loon (2014). Is there a need for protein ingestion during exercise? Sports Med 44(supp1) 105-111.
(5) Pasiakos et al (2011) Chocolate Milk & Endurance Exercise Recovery: Protein Balance, Glycogen & Performance. Medicine and Science in Sports and Exercise, 2011 Sep 7. [Epub ahead of print].
(6) Res et al (2012) Protein ingestion prior to sleep improves overnight recovery. Med Sci Sports Exerc 44(8). 1560-1569