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Home :: Muscle Building Nutrition :: Protein


Why does the body need protein?

Protein is important for muscle growth. Protein from your food is broken down into individual amino acids during digestion and absorption. The amino acids are then taken up by the body for various functions such as manufacturing tissue and the enzymes needed for metabolism. Everyone needs protein, but the needs of strength trainers are higher than those of endurance athletes. Protein is a nutrient made up of amino acids. There are two types of amino acids. Non-essential Amino Acids that can usually be synthesized by a healthy body from the daily foods that we eat. Then there are Essential Amino Acids that must be obtained through the daily diet.

Without protein, you cannot build muscle tissue. In your diet, you will incorporate approximately one portion of protein with every meal. This will help build muscle tissue and give you a leaner body.

Protein has a number of important roles in the body, including:

  • Repairing of body cells.
  • Building and repairing muscles and bones.
  • Providing a source of energy.
  • Regulating many important metabolic processes in the body.

Some other high protein foods are:

  • Chicken.
  • Lean Meats.
  • Egg Whites.
  • Turkey.
  • Tuna Fish (and other seafoods).

Why should strength trainers eat more protein?

Heavy strength training stimulates an increased uptake of amino acids from the bloodstream. These amino acids are then built up into new contractile muscle proteins, actin and myosin. To build muscle, you must take in more protein than you excrete i,e, be in a 'positive nitrogen balance'. A deficiency will result in slower gains in strength, size and mass, or even muscle loss ­
despite hard training. However, there is not a linear relationship between protein intake and muscle growth. Muscle growth depends not only on your protein intake but also on the intensity of your training (i.e. the training stimulus) and your genetic potential for muscle growth.

In practice the body can adapt to variations in protein intake. For example, as you gain experience the body becomes more efficient in conserving it so you break down less muscle proteins during intense training. This is often sufficient to maintain an anabolic environment and induce muscle growth. Therefore, advanced strength trainers may need less dietary protein/kg body weight compared with novice strength trainers. One study found that the protein requirement/kg body weight of advanced strength trainers was 40% less than those of novice strength trainers.

It is generally recommended that strength trainers need 1.4-1.8 g/kg body weight/ day19, 20 compared with the Recommended Daily Allowance (RDA) of 0.75g/kg body weight/ day.

For a 75 kg strength trainer:

Protein needs = (75 x 1.4)-(75 x 1.8) = 105-135 g/day

Should I eat too much protein?

Consuming more than 1.8 g protein/kg body weight/ day will not make you more stronger or more muscular. As mentioned, there is not a linear relationship between protein intake and strength or muscle size. In a study of strength athletes carried out at McMaster University, Ontario, athletes consuming either 1.4 g/kg body weight/ day or 2.3 g/kg body weight/ day experienced similar increases in muscle mass. Those with the higher protein intake gained no further benefits. Once your optimal intake has been reached, additional protein is not converted into muscle.

How can I meet my protein needs?

You should get the majority of your protein from food sources rather than supplements. Animal sources (chicken, turkey, fish, lean cuts of meat, low-fat dairy products and eggs) generally have a higher biological value (BV) (see table below) than plant sources (tofu, quom, beans, lentils, nuts and cereals) but the key with protein is to include as great a variety as possible. If you eat a mixture of animal and plant sources, you get a good variety of amino acids as well as a better range of other nutrients (fibre, vitamins, minerals and carbohydrate).The protein content of various foods is given in the table below.

Protein Content of Various Food


Portion Size

Protein (g)

Meat and Fish

Beef-fillet steak, grilled

105 g


Chicken breast-grilled, meat only

130 g


Turkey-light meat, roasted

140 g



120 g



150 g


1 small tin tuna-canned in brine

100 g


Dairy Products


Cheese, cheddar (1 thick slice)

40 g


1 small cartoon cottage cheese

112 g


1 glass skimmed milk

200 ml


1 cartoon low-fat yoghurt-fruit

150 g


Eggs (size 2)



Nuts and Seeds


Peanuts-roasted and salted(handful)

50 g


Peanut butter on 1 slice bread

20 g


Cashew nuts-roasted and salted(handful)

50 g


2 tbsp sesame seeds

24 g




1 small tin baked beans

205 g


3 tbsp red lentils-boiled

120 g


3 tbsp red kidney beans-boiled

120 g


Soya and quorn products


2 tbsp dry soya mince

30 g


Tofu burger

60 g


4 tbsp quorn mince

100 g


Grains and Cereals


2 slices wholemeal bread

76 g


1 bowl pasta-boiled

230 g


Should I take protein and meal replacement supplements?

There are two main reasons for taking protein and, meal replacement supplements: convenience and to increase protein intake. Protein foods require a certain amount of preparation; supplements just need mixing with water or milk. However, supplements offer nothing intrinsically different from food, and possess no miracle ingredient that will enhance your muscle size.

From a nutritional viewpoint, supplements can be justified if:

  • You have particularly high protein requirements (e.g. high body weight and/or you are undergoing heavy training) and find it - difficult to consume sufficient quantities from food.
  • You are on a calorie-restricted diet ­additional protein can offset muscle breakdown and a supplement can provide
    protein without extra calories from carbohydrate or fat.
  • You eat a vegetarian or vegan diet - most plant sources contain considerably less protein per gram compared with animal sources, making it more difficult to meet your needs from food alone.

If in doubt, keep a record of your usual food intake over a few days, then compare your actual protein intake (see Table above) with your requirement. If there is a consistent shortfall, consider adding a supplement. For example, if you weigh 80 kg, you may need as much as 144 g protein/ day (based on 1.8 g/kg body weight/ day), which is difficult to get from food alone - and more difficult if you are vegetarian.

If you want to get more information about supplements and buy them then go to our supplements section.

Which type of supplement should I choose?

First you need to decide whether you need a protein powder or an meal replacement product. Protein powders basically supplement your protein intake; meal replacement products are designed to provide a well­balanced 'meal'. In addition to protein, they also provide carbohydrate, vitamins, minerals and various ergogenic substances and as such they are particularly convenient as a post­workout meal. You should also consider the source of the protein (whey, casein, soya, milk etc.), the taste, cost, ease of mixing and whether you are intolerant to any of the ingredients (e.g. lactose, casein). The various positive and negative points of protein sources are summarized in Table below.

Protein Positive and Negative Points

Protein Source

Derived from

Positive Points

Negative Points


A by-product of cheese manufacture

Excellent ratio of indispencable amino acids including the branched chained amino acids.

Higher biological value than other proteins.

Raises glutathione levels, which stimulates immune system.

Relatively expensive.

Needs a blender to mix well.



Slower to digest, longer transit through gut, so protein may be absorbed more completely.

High glutamine content makes it immune boosting.

"Anti- catabolic"-i.e. reduces muscle breakdown.

Good ratio of indispensable amino acids.

Lower branched chained amino acids then whey.

Relatively expensive.



"Supro"soy isolate has high branched chained amino acids content of glutamine and arginine.

Numerous health benefits including cholesterol lowering and prevention of certain cancers.

Variable quality depending on manufacturing process.

Relatively expensive.

Milk protein

Skimmed milk

Good amino acid profile.

Low cost.

Unsuitable for those with lactose intolerance.

Lower biological value then whey or casein.

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Muscle Building Nutrition - Protein