Protein, Reality. Protein is an essential macronutrient for humans, since it is the basis for the formation of structures, organs, skin, hair, everything you imagine needs protein. It's key. Therefore, its deficiency will bring us problems, such as weakness, fatigue, loss of muscle mass, depression, loss of mood, sarcopenia among other metabolic problems. The basic requirement for any human being is stipulated in 0.8 grams / kg of weight, only to maintain a stable or slightly positive nitrogen balance. For someone active it can go up to 1.3gr / kg. For someone who weightlift 1.5 to 3.2gr / kg. For someone who does aerobic sport 1.5 to 2. These amounts of protein are SAFE, there are no dangers of kidney problems, liver, or anything like that, they are myths and there is enough scientific evidence that they are safe figures and you could even consume more without any problem. If you keep a protein deficit for a long time you will find yourself with a terrible muscle loss, fatigue, nitrogen balance logically negative, little recovery day by day, possibility of injury with basic activities, basically you do not want to be in deficit. Set the amount of protein you need and try to meet it is key, but in the medium term you might encounter some difficulties.