Obesity is a disease and a growing health threat all over the world.

Weight loss
diets don't always work in the long term, and many people just can't get into the habit to eat more healthy food. So the development of drugs which can handle obesity was almost unavoidable.

The prescription drugs listed below are used for many problems other than depression, including: insomnia, obsessive-compulsive disorder, fibromyalgia, anxiety and more.

It is important to understand why you have been prescribed these medications and to be assertive with your caregivers if you feel you are having complications that outweigh the benefits of using them. There may be another medication that offers more benefits with fewer side effects, so you should ask about other possibilities. (With some drugs weight gain has been reported!)

The Department of Nutrition and Bromatology of the Faculty of Pharmacy of Gasteiz, University of the Basque Country, is studying the action mechanism of fluoxetine in genetically fattened rats. Due to fluoxetine, those rats eat 50 % less. Therefore, the bodies put on less weight and the size of different fat tissues is reduced.

Antidepressants of the type of fluoxetine reduce appetite. More exactly, fluoxetine affects on neuropeptides that regulate appetite. Hence, it is believed that fluoxetine can be used to treat obesity.

After studying the action-mechanism of fluoxetine it has been observed that it reduces the quantity of Y neuropeptide. That peptide is orexigen, it causes appetite. The fluoxetine does hinders the trasport of that peptide, and so appetite is reduced.

Appetite is a feeling that is created in the hypothalamus and its regulation is a complex process that depends on the regulation of neuropeptides, neurotransmitters and several hormones. In that process two types of neuropeptides must be taken into account: orexigens or appetite stimulants and anorexigens or reducers of appetite. Both have effect on the hypothalamus and their interaction causes hunger and satiety.

Anti-smoking drug Zyban - a form of bupropion

Obese patients who took a medication called bupropion hydrochloride - a form of which Zyban, is used to help people give up smoking - lost significant amounts of weight over a 24-week period.

Follow-up research showed that the patients who continued taking the medication for another 24 weeks kept the weight off. A total of 227 patients completed the initial 24 weeks of the course, and 192 completed the full 48 weeks. More than 200 clinically obese men and women took part in the study. None of them were clinically depressed. The people who combined the medication with diet and exercise lost significantly more than those who just followed the diet and exercise regime. Those who took 400mg/day of Bupropion lost a greater percentage of their initial body weight than those who took 300mg/day. Some patients who took the medication experienced side effects such as headache, dry mouth and diarrhoea.

Lead researcher Professor James Anderson, of the University of Kentucky College of Medicine said: "We are encouraged by these preliminary results in non-depressed obese patients.

Researchers at Harvard University in the USA have discovered that the drug bupropion, which is used for depression and smoking cessation, is helpful in helping women sustain weight loss.

They gave 50 non-depressed overweight and obese women bupropion or placebo for eight weeks and put them on a 1,500 calorie per day diet. Two thirds of those on bupropion lost more than five per cent of their body weight, while only 15 per cent in the placebo group lost weight. They continued for another 16 weeks, after which time those on bupropion lost nearly 10 per cent of their body weight, on average, of which 70 per cent was fat. The benefits were maintained during two years of follow-up.

The drug bupropion can help overweight and obese women lose weight in the long-term. It was reported to decrease food intake and weight.

It is not known how bupropion works in weight loss, although it's known to alter brain chemistry and may affect the appetite centres or circuits involved in getting pleasurable feelings from eating.

Prozac (Ladose) - fluoxetine hydrochloride

Professor Ian MacDonald, an expert in metabolic physiology at Nottingham University, told BBC News Online that Prozac had also shown promise as a potential treatment for obesity.

Prozac reduces food intake and is associated with weight loss in depressed and otherwise healthy individuals.

Sibutramine (Reductil), which is currently used to treat obesity, was initially developed as an antidepressant.

Celexa (Seropram) - citalopram

Researces find out that citalopram reduces appetite for sweets, significantly reduced binge eating episodes and has a weight loss effect.

Professor MacDonald said: "It is not surprising that anti-depressants help some people lose weight. They act to improve mood and perceptions of self-worth so that people are better able to yes I can stick to this diet. There was also some evidence to suggest that antidepressants acted on the same areas of the brain that control food intake and appetite.

Taking antidepressant drugs can help seriously overweight people to lose weight, research suggests.