Although normally a large man will be able to hold more liquor than a small man, the development of high tolerance throws this off completely. A tolerant alcoholic who weighs no more than 120 pounds soaking wet can often drink a linebacker under the table - and drive him home. Not everyone who has tolerance for alcohol becomes an alcoholic, but just about every alcoholic shows an abnormal tolerance for the drug. Dependence involves withdrawal symptoms. The late ones are still more incapacitating, and may include convulsions and hallucinations.
Physical dependence is difficult to explain.
It was once popularly believed that you were required to drink a great deal of alcohol over an extended period to become physically dependent, but there is increasing evidence that many alcoholics develop withdrawal symptoms early in their drinking career, before extensive drinking has occurred. Once withdrawal symptoms begin, it's only a matter of time before the alcoholic discovers that more alcohol will eliminate, or at least alleviate, them. When the disease has reached the point where he drinks continually for extended periods, then his only real motivation for drinking, no matter what excuse he makes, is simply that the last drink has worn off. The third primary symptom involves changes in the body's organs, which means that alcohol has done measurable damage to the body. This could be in the form of an enlarged liver, pancreatitis, kidney disorders, neuropathy, myopathy, and the whole range of alcohol - related health problems.