Smoking reduces calorie intake by affecting levels of hunger hormone ghrelin in the body, says a small study presented at the European Respiratory Society International Congress.

Smoking and weight loss have been associated before but it wasn't exactly clear how smoking cigarettes causes a drop in a smoker's weight. According to earlier research, it may be related to hormonal activity.

Now, a study carried out by Dr. Konstantina Zachari and colleagues at the Harokopio University Athens, with Athens Medical School Greece as a collaborator, is saying that it's because smoking causes a drop in ghrelin. With the hunger hormone low, hunger levels are also down, leading to a reduction in food (and thus, calories) consumed.

For the study, the researchers worked with 14 healthy males who underwent two trials after abstaining from smoking and food. In the first trial, the subjects smoked two cigarettes from their brand of choice, while they simply held a cigarette as if smoking it for the second trial, the control trial.

Each trial was set for 15 minutes. Forty-five minutes after each one, the subjects were given the liberty to eat whatever snacks they wanted. Dietary intake, appetite feelings (desire to eat, hunger, satiety), and craving for smoking were then recorded at standard time points and samples of blood were collected to test for the hormones ghrelin, obestatin, insulin, CCK and GLP-1.

Overall, the researchers saw a drop in dietary intake, resulting in a reduction of 152 calories. Additionally, plasma ghrelin concentrations were lower after the control trial.

The trials, however, had no effect on macronutrient intake or taste preference. Appetite feelings and levels of obestatin, insulin, CCK and GLP-1 were also unaffected.

The belief that smoking helps in regulating body weight starts with adolescent smokers and sticks well into their adulthood. As such, many who may be looking to control their weight may be demotivated to quit smoking, even with the realization of its harmful effects to health. Their worries may also be supported by their own experience or that of others where weight is gained after smoking cessation.

The researchers acknowledge this, pointing out the need to further investigate other possible biological mediators to help come up with ways to address post-cessation weight gain while still promoting smoking cessation and lowering relapse rates.

To help smokers quit, Britain's Royal College of Physicians has thrown its weight behind e-cigarettes. They may still have their dangers but e-cigarettes are healthier alternatives to smoking, at least in that they have fewer cancer-causing chemicals than standard cigarettes.