The burning of tobacco generates in excess of 4,000 compounds. The component of most notoriety is nicotine, which is both a stimulant and depressant, depending on timing and dosage. While nicotine has been associated with what we interpret as desirable effects (including elevations of mood, mental acuity and several aspects of cognitive performance, as well as an increased metabolic rate and suppression of appetite) it ultimately has negative effects on physiological capacities and growth, and it increases the risk of heart disease and stroke. Other components of tobacco are causative agents in a variety of pulmonary diseases and cancers.
Well-documented effects of nicotine include increases in the secretion of anti-inflammatory, excitatory and catabolic hormones from the adrenal glands (epinephrine, norepinephrine, cortisol and other hydroxycorticosteroids); elevations in gluconeogenesis (which entails conversion and diversion of amino acids from protein synthesis to energy production); increases in blood lipids; fluid retention; impaired peripheral circulation; and, possibly, reduced fertility.
Smokers also have more sleep difficulties than nonsmokers and tend to exhibit more depression, irritability and anxiety.
Women experience very significant effects from smoking, as do the fetuses of pregnant women who smoke. Osteoporosis has been documented in male smokers and is a much more significant problem in women smokers than in nonsmokers. And some studies have shown that male smokers have higher estrogen and lower plasma-testosterone levels than nonsmokers do.
Bottom line: The hormonal and metabolic effects of tobacco, whether smoked or taken orally, lead to degradation of mental and physical energy, endurance and recovery.
If you're a smoker, quit smoking now. As you can discern from just this smattering of information (and I barely scratched the surface of smoking's disadvantages) it's a serious threat to your bodybuilding interests.
Once you have quit smoking its time to see if you have enough will power and mental strength to be a bodybuilder. This is a sport that requires, more than anything, strength of character and powerful self-discipline. Every day, you need to challenge yourself and win. You need to face your weaknesses and fears, and you must overcome them. You must take yourself beyond your perceived limits. That's what a workout is: making yourself do something you didn't think was possible.