I had 4 beers last night around 9pm how long will it be in my system?

Depends on how: you are tested. The alcohol per se is gone, but its effects on some of the proteins and organs linger longer. A test called Ethyl glucoronide, a urine test may be positive for up to 5 days after the last drink. if the four beers were part a chronic drinking habit, a test called CDT may be positive for up to 14 days. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.