Smokers’ poor diet explains why quitting leads to weight gain

A massive new study has found that smokers, on average, have worse diets than non-smokers. And the researchers concluded that this led to many people who quit smoking facing a new health problem – gaining weight.

The study authors said smokers ate less food but were more likely to find fried foods and add salt and sugar to their meals than nonsmokers. They said the findings of the research, involving around 83,000 British adults, could explain why smokers tend to gain weight when they kick the habit.

Previous research has already shown that people who smoke tend to have a lower body weight and body mass index (BMI) than their non-smoking counterparts, while quitting smoking is associated with weight gain.

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An important factor is that nicotine can suppress appetite and some people may even smoke to help them stay slim. Researchers from Loughborough University and the University of Leicester looked at associations between smoking and food and eating habits.

The study was based on data collected during health assessment programs between 2004 and 2022 by the charity Nuffield Health. The 83,000 adults filled out questionnaires about their usual eating habits, and their BMI was also measured during the assessments.

The research found:

• Smokers were twice as likely to skip meals and 50% more likely to go more than three hours without food compared to non-smokers.
• Smokers were more likely to have fewer meals per day
• Smokers were also 35% less likely to snack between meals and were also less likely to eat food as a reward or out of boredom than non-smokers
• Compared to nonsmokers, smokers were also 8 percent to 13 percent less likely to eat sweet foods between meals and have dessert.
• Smokers were eight percent more likely to eat fried food
• Smokers were 70% more likely to add salt to their meals
• Smokers were 36% more likely to add sugar to what they ate

The research team said the most consistent observation was that the relationships were stronger in older people. The relationship between smoking and a greater likelihood of adding salt and sugar to meals was also stronger in men compared to women, suggesting that men who smoke may be particularly susceptible to less healthy eating habits.

Lead investigator Dr Scott Willis from Loughborough University said: ‘Worry about gaining weight is a common reason why smokers do not try to quit or are unsuccessful in their attempts to quit. Our findings indicate that smoking is associated with eating behavior patterns consistent with reduced food intake and poorer diet quality, characterized by frequent consumption of fried foods and added salt and sugar to meals.

“This could explain the weight gain commonly seen when people quit smoking.”

Lead author Arwa Alruwaili, a PhD researcher at Loughborough University, said: “These findings reinforce the importance of providing nutritional support and weight management in large-scale efforts to prevent and reduce smoking in the general population in the UK.

“This could help promote more successful quit attempts and improve people’s eating habits and the many diseases that are linked to both of these major health risks.”

The results are to be presented at the European Congress on Obesity (ECO) in Venice, Italy.