It is not yet properly understood why different people show different kinds of reactions to alcohol abuse. There are people who may get inebriated with only a few sips of an alcoholic beverage, while there are also people who will not show any effects even if they have had several glasses of the beverage.

This differential behavior of people towards alcohol has always been a subject of medical study and a lot of consternation. Alcohol addiction treatment programs delve a lot on this sustainability of people towards alcohol, which is scientifically termed as alcohol tolerance.The reason for people acting differently towards alcohol addiction probably lies in the liver. The enzymes that facilitate the breakdown of alcohol reside in the liver. However, these enzymes do not act in the same amount for everyone. In some people, the enzyme can exhibit a high activity, due to which alcohol (ethanol) is converted into acetaldehyde, which is toxic for the body. When this happens, the person rejects any further alcohol drink. Due to this, people with high activities of this enzyme will consume less alcohol doses. This has been observed even among alcoholics themselves. Alcohol consumers who have a high activity of this enzyme will consume lower alcohol than others.

However, after years of alcohol consumption, this capability of the liver at metabolizing alcohol will increase. The liver will be acceptable to higher alcohol doses and due to this there will be more alcohol consumed. The direct effect of this is damage to the liver.