Smoking: how it affects diet & nutrition

Q: How does smoking suppress appetite? What effect can this have on a person’s health?

Nicotine suppresses appetite because of its effect on the brain and the central nervous system. Nicotine does not damage a person's health – it is the tar and carbon monoxide from the cigarettes that can cause cancer, lung disease and coronary heart disease. A varied and healthy diet is important for people's health, and stopping smoking will increase your enjoyment of a wider number of foods.

Q. Will I gain weight if I stop smoking?

The average weight gain after stopping smoking is 4-5 kgs, although people who smoke more heavily tend to gain more weight. Most of the weight gain occurs in the first three months after quitting; after six months of stopping most people have lost some of this weight.

Weight gain occurs as stopping smoking reduces metabolism. While this change in metabolism is relatively small (the equivalent of about 150kcals/day), weight gain will often occur because people who stop smoking tend to eat more. This is because nicotine can suppress appetite, but also because food tastes better when you're no longer smoking. It's also common that people who give up turn to food to distract them from smoking. For some people, snacking keeps their hands busy or replaces the ‘hand-to-mouth’ action of smoking.

Gaining weight is not inevitable, however. Making some small changes to eating and physical activity can go a long way in addressing weight gain. This includes eating healthy snacks, ensuring regular meals and not over-eating. Planning ahead so healthy snacks are on hand will help. A brisk walk or other exercise will burn calories and help to maintain a healthy weight. Walking and exercise when you stop smoking is also recommended to help relax, manage stress, and keep you busy.

Q: How does smoking affect your sense of smell and what effect does this have on diet and nutrition?

Smoking irritates the nasal passage which can cause inflammation and impair your sense of smell. This is unlikely to directly affect diet and nutrition but will undoubtedly influence your enjoyment of food.

Q: What effect does smoking have on your absorption of nutrients? Which nutrients suffer the most?

Smoking affects the body's ability to absorb a variety of vitamins and minerals including calcium and vitamins C and D. Smoking also affects the body's circulation by causing blood vessels to narrow and become blocked because of an increased build-up of fatty deposits. Stopping smoking is an effective method of helping avoid deficiencies of vitamins.

Q: How does giving up smoking affect your energy and fitness?

Stopping smoking has a hugely positive impact on a person's health, energy and fitness. The first two or three weeks of quitting can feel very difficult due to experiencing withdrawal symptoms and learning to cope with strong urges to smoke. However, after 48 hours the lungs are clear of carbon monoxide and by the end of day three breathing should become easier, bronchial tubes begin to relax and energy levels increase. After stopping smoking your circulation and lung function will also improve. People who stop smoking will find they do not become breathless so easily and will find it is easier to exercise. You can also expect better performance in aerobic exercise and athletics.

Compared to smokers, ex-smokers can expect to live longer, have fewer days of illness, have better fitness and energy levels, and be healthier and happier.

This article was last reviewed on 23 September 2024 by Dr Andy McEwen.

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