Smoking – bad for your health, good for your waistline? Overall, weight is lower in smokers and higher in those who quit, but we know that the relationship between smoking and weight is complicated and there’s a fair bit of research seeking to understand it better. Many people think that smoking can help them keep their weight down and fear that quitting will see them piling on the pounds.
I’ve blogged about this before. It was disappointing to find that a Cochrane review on interventions targeting weight gain after quitting smoking found too many gaps in the evidence to be clear about what works, though there were some interesting findings; weight management education did not reduce weight gain but did cut the number of quitters, while personalised weight management support looked promising (read more here). I also looked at a randomised trial of an intervention which aimed to promote healthier eating alongside smoking cessation. It seemed to improve diet without preventing weight gain, but more people who received the intervention quit smoking.
Now a cross-sectional study of over 40,000 adults from the six Scottish Health Surveys (1995 – 2010) has explored the relationship between smoking behaviour and being overweight or obese. These periodic surveys, which are done to assess the health and care needs of the population and aim to recruit different people each time, are conducted by trained interviewers who gather information relating to the person’s health and lifestyle. They also measure height and weight, much more accurate than relying on what people report themselves! Here’s what they found:
- In 16 – 24 year olds there was no significant association between smoking status and overweight or obesity, including no evidence of weight gain after quitting
- Overall, ex smokers were more likely to be overweight and obese than either never or current smokers, but
- people who had smoked for more than 20 years were more likely to be overweight than those who had smoked less and those who had never smoked
- People who smoked more than 20 cigarettes per day were more likely to be overweight than those who smoked less
This study has information about a large, representative sample of Scotland’s population and adjustments were made in the analyses for potentially influential (‘confounding’) factors such as socio-economic status. However, it is a snapshot from a particular moment and so it isn’t possible to look at how a person’s weight changed over time and conclusions can’t be drawn about possible causes. This type of study can only shed light on associations, not cause and effect.
The authors conclude:
This study adds to the evidence that whilst older smokers are less likely to be overweight than non-smokers, this does not appear to be the case for young smokers. Making this point in future educational campaigns aimed at young people may help to discourage them from starting to smoke.
Sounds like a sensible suggestion and something I’ll be interested to look out for when I’m gathering research on programmes designed to discourage children and young people from starting smoking. A Cochrane review on school-based programmes for preventing smoking has just been updated and we’ll be looking at that here at Lifestyle Elf HQ very soon.
Mackay et al.: Impact of smoking and smoking cessation on overweight and obesity: Scotland-wide, cross-sectional study on 40,036 participants. BMC Public Health 2013 13:348