• Appetite suppression. Caffeine may reduce your desire to eat for a brief time, but there's not enough evidence to show that long-term consumption aids weight loss.
• Calorie burning. Caffeine may stimulate thermogenesis — one way your body generates heat and energy from digesting food. But this probably isn't enough to produce significant weight loss.
• Water loss. In some people, caffeine can act as a diuretic, which means it increases the amount of urine you excrete. This increase in urine output, mostly water loss, may temporarily decrease your body weight, but it doesn't result in the loss of body fat.

Evidence seems to suggest that smoking cigarettes causes an increase in metabolic rate. Smoking may also suppress appetite.

However, the catastrophic health effects of smoking are far greater than the effects of obesity.

In addition, some health and weight studies show that weight loss among dieters who smoke cigarettes is less than among non-smokers.

Bottom line: if you're tempted to smoke in order to lose weight, DON'T!!