Smoking for weight control

It's another piece of conventional wisdom that quitting smoking causes weight gain. Just why that might be isn't quite clear, but explanations have ranged from smokers burning more calories as a result of their smoking to ex-smokers turning to eating as a substitute for smoking. But as we saw with "salty foods make you thirsty" last week, sometimes the conventional wisdom just hasn't really been investigated scientifically.

A team of scientists in Oregon designed a prospective study to look at weight status among female college students: specifically comparing smokers to non-smokers (Appetite 2015;85:155-159). They note in their article that the largest age group of smokers in the United States are those between the ages of 18 and 24, and that college-age women often cite "weight control" as their reason for continuing (or starting) smoking. On the other hand, what's often the biggest concern for those who are thinking about quitting smoking? Weight gain.

The team recruited almost 400 women from a local university "with body image concerns" to participate in a body acceptance program. Of those participants, 29 were smokers. The women were randomly assigned to either a once-weekly group-based eating disorder prevention program that met for 4 weeks or provided with an educational brochure on eating disorders. At the start of the study, and at 1 month, 6 months, 1 year, and 2 years, the participants responded to questionnaires that included questions about smoking - whether they did, and if so, how much. Their height and weight were also measured at each interval.

About half (48%) of those who reported smoking said that they smoked on a daily or near-daily basis, but the majority of those (55%) said that they smoked only 1-2 cigarettes per day. Only 21% of the smokers reported smoking 9 cigarettes or more on those days they smoked.

Interestingly, those women who reported smoking had higher Body Mass Indices at the start of the study, with a BMI average of 25 compared to non-smokers' average of 23.5 (25 is considered the upper limit of "normal weight"). Over the course of the two years of the study, those who began the study as smokers and continued smoking throughout the study gained an average of 1.4 kilograms (about 3 pounds), and those who quit smoking during the study gained an average of 4.8 kilograms (about 10.6 pounds). Those who never smoked, however, gained an average of only 0.9 kilograms (about 2 pounds).

This would appear to explode the idea that smoking helps with weight control, but keep in mind that those who smoked weighed more at the start of the study and all of the participants had body image problems. Those who are struggling with their weight and using such ineffective yet popular measures as smoking, using diet supplements, taking appetite suppressants, or using laxatives tend to gain more weight over time than those who take a healthier approach to managing their weight.

What this means for you

If you are thinking about quitting smoking, don't despair! You can learn to manage your weight in a healthful way without resorting to unhealthy habits or ineffective quack medicines.

First posted: December 31, 2014