By Sally Robertson
People seem to gain more weight after giving up smoking than has previously been estimated, report researchers.
A significant proportion of individuals who try to quit can expect to put on 4 to 5 kg in weight after just 1 year of quitting, they warn.
This estimate is "substantially higher than the 2.9 kg often quoted in smoking cessation advice leaflets," remark Henri-Jean Aubin (Université Paris-Sud, Paris, France) and colleagues in the BMJ.
"Moreover, this mean weight gain is greater than the 2.3 kg gain that female smokers report being willing to tolerate… before embarking on quitting," they note.
The findings come from a meta-analysis of data derived from 62 trials of smoking cessation interventions published in the Central Register of Controlled Trials and Cochrane reviews.
The trial review showed that after 1 year of quitting, smokers gained about 1 kg in weight, regardless of whether or not they were provided with anti-smoking aids such as nicotine replacement therapy.
Among untreated patients, this mean weight gain further increased to 2.26 kg, 2.85 kg, 4.23 kg, and 4.67 kg at 2, 3, 6 and 12 months, respectively, after quitting. And the estimates were again similar for individuals who used the support of smoking aids.
However, there was a significant variation across the study population in the amount of weight gained.
At 12 months, 16-21% of patients had lost weight, 35-38% had gained less than 5 kg, 29-34% had gained 5-10 kg, and 13-14% had gained more than 10 kg.
"Variation in weight gain… is rarely described or discussed in the literature, and has clinical implications," says the team.
"Some people are either destined or able to prevent weight gain without intervention, whereas others seem likely to gain enough weight that puts them at increased risk of diabetes, among other complications," say Aubin and team.
Further research should identify the subgroups most at risk of gaining weight and clarify the optimum content and timing of intervention to prevent weight gain after cessation, conclude the researchers.
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