The recommended minimum daily intake for protein is 0.30 grams per pound of body weight for women and 0.35 grams for men which is about 45 grams of protein for a woman weighing 150 pounds (68 kilograms) and 52 grams for a man of equal weight. To put this into context, a cup (250g) of low-fat Greek yogurt has about 15 grams of protein and a serving of skinless chicken breast (110g) has about 25 grams of protein. However, this is the minimum daily recommendation that you need for basic protein synthesis and will not produce optimal health and body composition results. You should ideally target between 0.40 and 0.50 grams of protein per pound of bodyweight if you are a woman and 0.45 to 0.55 grams if you are a man.
If you experience swelling of the abdomen, swelling of the hands or feet, mood changes, hair and skin problems, fatigue, hunger, slow-healing injuries and getting sick then you may be suffering from protein deficiency, so you probably want to increase your protein intake.
Protein is also essential for muscle growth so if you want to build muscle then you will need to increase your protein (you can think of protein as filling in the cracks in your muscles). However, there is an upper limit to your protein intake. If you consume more protein than your body needs, then the excess protein will eventually be stored as fat leading to weight gain. And too much protein can result in health problems like kidney disease, higher cholesterol and cardiovascular risk. So, unless you are a professional athlete or body builder, you will want to stay below 0.85 grams per pound of body weight if you are a woman and 0.90 grams if you are a man.
 For metric conversions: 0.4g per lb is 0.9g per kg; 0.5g per lb is 1.1g per kg; and 0.6g per lb is 1.3 g per kg.