MYTH: Smoking helps me stay thin and fit
FACT: It is true that most people put on weight when they stop smoking. Smoking is more damaging to your health than being slightly overweight.
You would have a BMI of 35 or more to have the same risks as smoking.
Smoking certainly does not keep you fit, it reduces physical fitness and endurance by cutting down the amount of oxygen available in the body and forcing the heart to work harder.
It also increases fatigue during and after exercise.