A man’s  recommended daily allowance of protein is 55.5g, but  exact requirement depends on body weight and the intensity of physical activity. For instance, an adult  looking to build muscle mass should have 1.5 – 1.7g of protein per kilo of body weight each day.

Protein contains four calories per gram and it’s made of building block known as amino acids. There are around 20 different amino acids commonly found in plant and animal proteins, 11 of them are non-essential amino acids, meaning that your body can make them by itself. The other nine can be acquired through  our diet.

Food that contains all nine essential amino acids, such as egg, meat and fish, are known as complete proteins and are the best for building muscles. Foods lacking one or more amino acids are usually plant proteins such as nuts and grains, so you need to complete the protein by combining it with other food that contain the missing acids.  Beans and toast, for instance, can create a compete protein.

How protein works

Protein represents about 20% of body weight. It’s present in every cell in the body, from your muscles and internal organs to your skins and hair.

Your body uses protein for  a variety of functions, including tissue repair, forming enzymes and hormones and transporting nutrients.  Protein can be converted into  glucose, through a process called gluconeogensis – and used as energy.

Muscles are basically stored protein. when you eat protein, it’s digested and broken down into amino acids. These are absorbed and released into the blood stream, then delivered to new sites in the body where new proteins are needed. This is where amino acids are assembled into new proteins, a process called protein synthesis.

As  new  stores   of protein are built, old ones are broken down and used for protein’s many functions. If protein synthesis occurs at the same rate as protein breakdown, you’re are in what’s known as protein balance. As for muscle growth,  you  have to create a positive protein balance by allowing the body to retain more dietary protein than it uses  or excretes.

If you don’t eat enough, your body converts more proteins into glucose, which could leave you with negative protein balance. This is why crash-dieters lose muscle and why it can be hard to  gain muscle and lose fat at the same time.