Research has stated that once smokers drop the habit they tend to gain about five kilos of weight.

It was seen by researchers from the UK and France that an average of about 4.67kg of weight was put on by former smokers after they dumped the habit in about a year's time.

They also saw that it was during the first three months that most of the weight was put on.

An average of about 2.85kg of weight was put on by smokers in the first three months after leaving smoking and this was seen after analysing the results from 62 studies.

When it came to weight change, there was a lot of variation seen by researchers and more than 10 kg was gained by 13 per cent of people and some weight was lost by 16 per cent of people.

Researchers have however stated that the benefits of quitting the habit outweigh the excess weight gain.

Esteve Fernandez, associate professor of epidemiology at the University of Barcelona, and Simon Chapman, professor of public health at the University of Sydney, said, "The relative long-term health effects of weight gain and smoking cessation also need to be considered with respect to the ultimate public health message that we should derive from this and future studies."