Proteins have a wide range of functions in the body – they form structures such as hair, skin and muscle, and they send signals around the body in the form of hormones.
[related_articles]They’re also used to rebuild tissue after exercise, and prepare muscles for further exersions – making them very important if you're working out regularly.
All proteins are not made equal. Proteins are actually made up of 20 amino acids - nine of which are 'essential' - meaning they aren't produced in the body and you can only get them through consuming foods that contain them. Foods that contain more of the amino acids responsible for building muscle are the most important for those who exercise heavily.
Here are some of the best sources…
Eggs provide a complete protein - in fact a whole egg contains 18 amino acids, including all the 'essential' amino acids. Whether scrambled, poached or even fried, eggs are delivering a healthy helping of all the good stuff to your muscles.
Some people opt to eat just egg whites, because the yolk is high in cholesterol, at around 62% of your recommended daily intake per egg. You'll get more nutrients from the entire egg, and it's only worth considering leaving the yolk if you're consuming more than two on a regular basis.
A medium egg contains 63 calories, 6g of protein, 4g of fat and no carbohydrate - so eggs on wholemeal toast will be best to make sure you restore glycogen stores.
Another complete protein source is milk - it contains 18 amino acids, including all essential amino acids, and it's delivered to the muscles quickly.
Unfortunately, soy milk has been shown to have a lesser effect on muscle repair than protein from cows milk. You can buy lactose-free cows milk if you're staying away from it.
Milk protein consists casein and whey proteins - whey is particularly quick to be absorbed, and thus used in a vast number of protein powders.
One 244g cup of whole milk contains 146 calories, 8g of fat, 13g of carbohydrate, and 8g of protein, plus a healthy dose of 28% of recommended daily calcium intake. Skim (1% fat) milk contains 102 calories, 2g of fat and the same amount of protein and carbs.
Made from milk, yoghurt provides similar nutrition, but with the addition of gut friendly bacteria that keeps your stomach happy and healthy.
Greek yoghurt is particularly high in protein, and tasty thanks to its thick, creamy texture. A 200g cup of the full fat variety contains 190 calories, 10g of fat, 8g of carbohydrate and 18g of complete protein.
Meat products contain all nine essential amino acids, making them quality proteins. Most poultry meats are great options, but turkey is particularity lean.
An average roast turkey breast, without skin, contains 153 calories, 0.8g of fat and 34g of protein, with no carbohydrates.
Competitively, an average chicken breast, without skin, contains 124 calories, 1.4g of fat, no carbohydrate, and 26g of protein. Pork is the fattiest, with 35g in an average pork chop but around 7.5g of fat.
Whichever meat you go for, if you team it with 100g of brown rice, and you'll also get 23g or carbohydrate and 3g of protein, though this isn't a complete protein and doesn't contain all essential amino acids as meat does.
Red meat is usually higher in cholesterol and saturated fat than poultry, so many athletes take it off the menu, but it's also high in iron, protein, and creatine.
Iron is particularly important for women, who typically need 18mg of iron a day, as opposed to the 8mg men need - low Iron levels can result in fatigue.
Creatine is often taken as a supplement by body builders and athletes, as it is an amino acid which helps to build explosive muscle (useful for sprinters particularly). Beef is also high in leucine, another amino acid responsible for helping put protein to good use in the muscles.
It is worth noting that red meats, such as steak, are slower to digest. This means they keep you feeling full for longer, so paired with salad, they're great if you're trying to lose weight. However, they won't deliver repairing nutrients to your muscles quickly, so are best not used as a post-workout meal.
An average steak (just over 100g) contains 207 calories, 6.5g of fat, and 34.5g of protein, and around 22% of your daily cholesterol recommendation.
Salmon or Tuna
Fish is a great source of protein, that also contains plenty of Omega 3 and good fat.
An average 100g serving of salmon contains just over 200 calories, 12g of fat, but only 3g of saturated fat, and 22g of protein.
Fresh tuna packs in 26g of protein per 100g, and only 116 calories thanks to its lower fat content, of less than a gram.
Vegans may be wondering where they can get complete proteins from, if the most common varieties originate from eggs, milk or meat.
Quinoa is one of a few plant-based options that provide a complete protein, which contains all the essential amino acids to aid muscle repair and function.
One cup contains around 222 calories, with 3.6g of fat, 40g of carbohydrate and 8g of protein. You also get plenty of calcium and a lot of potassiumm from quinoa, which also helps to build and maintain muscle as well as regulating blood pressure.
Admittedly, the carbohydrate content is higher than most others on the list, but these would often be teamed with bread or rice to restore glycogen after exercise, so unless you're on a low carb diet, then that's no problem.
A second option for vegans is soy. Most beans are low in one or more of the the essential amino acids, but soy is a super bean that delivers a complete protein.
Tofu is great added to stir frys as a meat substitute. The firmer the tofu, the higher the protein content, with a typical serving containing 90 calories, 5g of fat, 2g of carb and 10g of the crucial protein.
Whey Protein Powder
Protein powders are a little controversial for some who prefer to get their nutrients from natural sources, but they can be incredibly convenient when you need a quick protein fix.
Powders can be made from animal sources (whey and casein, found in milk, beef protein and egg white protein), or vegetable sources (soy, rice, pea, hemp).
Values will vary, but typically 100g of Whey will contain 80-90g of protein, 80 calories, 3g of carb. The powder comes from milk - the protein in which comes from 20% whey and 80% caseiun.
Whey is quickly absorbed and the taste agrees with most people. Whey concentrate powders deliver the most whey per gram, whilst whey isolate versions contain almost zero fat so are popular among those trying to get leaner.
Another option is egg white protein, or beef protein. This is popular among weight lifters because beef naturally contains creatine - a substance that is known to improve explosive muscle strength. Sprinters, take note..
Soy Protein Powder
There are many vegan friendly powders, buy Soy is the most popular of plant based proteins, and it contains all the essential amino acids required.
It's been suggested in the past that Soy protein contains antioxidants, but there also some concerns that some of its properties could lead to both unwanted decreases in testosterone, and increases estrogen. Menopausal women have been advised to up their soy protein intake to regulate hormone changes, so it definitely has an effect.
In around 100g of Soy protein, you'll find about 90g of protein, 3g of carb, but but 321 calories along with 2g of fibre.
Want to know more? Check out these common myths about protein.