The government recommends that we eat 0.8g protein per Kg of bodyweight. If you weigh 70kg, then you only need 56g of protein. This is only enough to make sure that you're not deficient. However, when it comes to being active, losing body fat and getting great shape, we should be looking at over 1.8g protein per Kg of bodyweight. So that same 70kg person should be aiming for around 130-140g protein per day, or maybe more.
So why do we need so much more to get in shape?
To lose body fat, you need to be in a calorie deficit. This is where you are expending more calories on a daily basis through exercise, going to work, walking around and your body carrying out all its internal processes (like digestion etc...), than you are taking in from food and drink. So at some point, your body must dip into it's stores to meet this energy demand. If you're not getting enough protein from your diet, then your body may breakdown muscle tissue to meet these energy demands.
Protein has also bee shown in studies to prevent cravings and help you to feel full. Researchers have split people into 2 groups, a high protein group and a lower protein group. Both groups had the same overall calorie intake and so both groups lost similar amounts of weight and body fat. However the higher protein group reported fewer cravings and higher feelings of satiety after meals. So by having a decent helping of protein with each meal, you can maintain that calorie deficit without feeling hungry all the time.
When you eat foods, your body has to expend energy breaking them down and digesting them. Protein has a thermic effect after meals. This means when you eat foods like meats and fishes, your body burns more calories breaking them down. This isn't a a significant amount, however it does help protein to be the 'safest' nutrient to eat more of. So if you're feeling hungry, then snacking on something protein based can help you to quell the hunger without taking in too many extra calories.
And if you needed another thing to put your mind at ease; protein doesn't make you massive and bulky and musclebound (I wish it did!?) and nor does it damage your kidneys. Unless you have a pre-existing kidney condition, protein levels in excess of 4g per Kg of bodyweight have been shown to be safe... good luck eating that much!?
I hope this clears a few things up, but if you have any questions, feel free to drop me an email,