Why does smoking make people thin

Smoking and body weight

How does body weight develop in ex-smokers?

Smoking is widespread in our population and the cause of numerous serious illnesses. In contrast to many other highly developed countries, there is still broad social acceptance of smoking in Germany. In Germany in 2003 almost a third of the population aged 18 and under smoked, men with 37.3% smoked more frequently than women with 28% (24).

Smoking weakens the immune system and affects the health-related quality of life. Smoking can lead to heart attacks, strokes, arteriosclerosis, hypertension, pneumonia, chronic bronchitis and malignant tumors of the lungs, oral cavity, larynx, digestive organs and other organs (16, 37). Smoking is the single most significant cause of death and disease. Smoking cessation, on the other hand, is associated with a significant improvement in health. Data from the MONICA study show that the largest proportion of the observed decrease in heart attack mortality in men was caused by the decrease in smoking (21). Critchley & Capewell (2) also found in an evaluation of 20 cohort studies in CHD patients a significantly reduced mortality risk from smoking cessation.

"Reach for a lucky instead of a sweet" - in keeping with this former advertising slogan for cigarettes, many people are of the opinion that smoking can regulate their food intake and thus their body weight. A possible weight gain from quitting smoking is often rated more strongly than the health risks associated with smoking. Indeed, overweight or obesity is a common and significant risk factor for chronic diseases such as B. diabetes mellitus, high blood pressure, lipid metabolism disorders, cardiovascular diseases and psychosocial problems.

According to the nutrition report 2004 of the German Nutrition Society (DGE) e. V. (5), according to the results of the 1998 Federal Health Survey, more than 65% of men and approx. 55% of women in Germany are overweight.

Is there actually a connection between smoking behavior and body weight and does not smoking inevitably lead to weight gain? Does a smoker only have a choice between the health risks of smoking or those of weight gain? Can these two risks be weighed against each other at all?

Data on body weight development after smoking cessation

Concern about weight gain is often cited as a reason not to quit smoking or to start smoking again after quitting, especially by women (22, 38, 35, 32). Numerous studies have shown that smoking cessation is associated with weight gain, the extent of which can vary widely (40, 38, 36, 23, 28).

The following are selected study results shown. It should be emphasized that the literature has some methodological problems. The effect of smoking abstinence on body weight has often been examined retrospectively; there are only a few prospective studies that can better clarify the effect. However, the follow-up duration of the prospective studies is often short. Another limitation of many studies is, for example, that information on weight and smoking status is often based on verbal self-reports. There is a tendency to underestimate body weight (underreporting) and to give false information ("not admit") when it comes to smoking habits. It is also critical to compare results on abstinence at a specific point in time with those of continuous abstinence. Another difficulty is to separate the weight gain after smoking cessation from a "normal" weight gain. These are possible reasons for the sometimes inconsistent results.

O'Hara et al. (28) found, for example, in an evaluation of data from the Lung Health Study (1986-1994; prospective cohort study) relatively large weight gains within 5 years after quitting smoking. Among those who stopped smoking, 33% gained 10 kg or more, 7.6% of men and 19.1% of women gained 20 kg or more; in comparison, only 6% of smokers gained 10 kg or more.

Flegal et al. (8) retrospectively examined a population from the Third National Health and Nutrition Examination Survey (NHANES III) to determine whether smoking cessation is a factor contributing to the rising prevalence of obesity in the United States. They came to the conclusion that for men a quarter and for women a sixth of the increase in the prevalence of obesity can be due to smoking cessation within the last 10 years. The weight gain over 10 years was greater in ex-smokers by 4.4 kg for men and 5.0 kg for women than those who continued to smoke. Ex-smokers also have a higher risk of weight gain than people who never smoked.

For ex-smokers, Stumpfe and Kulig (35) describe on the basis of their own and other research results that approx. 35% feel hunger, approx. 60% have more appetite, approx. 60% observe an increase in weight and the weight increase in the first few months approx. 2.5 kg and after 6 to 12 months is approx. 4 kg. Furthermore, they assume that half of the weight gain will be lost again in the long term. The fact that heavy smokers (≥25 cigarettes per day) may initially experience significant weight gain (within 2 years), but then decrease again (after 5 years), B. also Mizoue et al. (26) found in a cross-sectional analysis of Japanese men.

Based on a cross-sectional analysis, Kawada (20) reports, similar to O'Hara (28) and Froom (10) in their prospective studies, of a period of weight gain of 5 to 7 years. In contrast, Williamson et al. (40) in the follow-up of an NHANES cohort (1971/75 to 1982/84) that the increased body weight is maintained regardless of the time since smoking.

In an older USDHHS report (38) based on the analysis of 15 study results on weight gain after smoking cessation, only moderate weight gain was reported: four fifths of people who quit smoking gained weight, the average weight gain was 2.3 kg. The average body weight gain of those who continued to smoke was 0.5 kg. Quitting smoking leads to a weight gain of approx. 2 kg greater than if you continued to smoke. This weight gain - especially when compared to smoking - does not represent a significant health risk. According to this report, the risk of large weight gains is low. Less than 4% of ex-smokers gain more than 10 kg. Even for these, the benefit of smoking cessation is given, and weight control programs should be implemented rather than allowing relapse to smoking (38).

In a more recent prospective study on a North German study population of 4,075 18- to 64-year-olds, John et al. (19) also that over a longer period of time (after 36 months) there was no significant weight gain due to smoking cessation. From this as well as from other studies (26, 28) there is evidence of a connection between the number of cigarettes smoked and the amount of weight gain after quitting smoking; Those who were heavy smokers gain more weight than those who were light smokers.

Causes of weight gain after smoking cessation

Nicotine causes an increased consumption of energy and smoking cessation accordingly lowers energy expenditure (27, 3). The increase in basal metabolic rate caused by nicotine is an effect that subsides within 24 hours (29, cited in 13), which is why quitting smoking can under certain circumstances affect body weight relatively quickly. Hofstetter et al. (15) found that heavy smoking (24 cigarettes per day) consumed around 200 kcal per 24 hours and concluded that a heavy smoker who stops smoking while eating the same food will experience weight gain in the long term.

Nicotine suppresses the appetiteso that after smoking cessation, appetite and food intake may be increased (27, 34, 18). The preference for sweets can increase (12, 11, cited in 13). In general, people who quit one addictive behavior, smoking, may be susceptible to replacing it with another deviant behavior (13).

In addition, nicotine seems to be a direct one Effect on adipose tissue to have, namely one decreased lipoprotein lipase activity and increased lipolysis. For example, if you quit nicotine and keep your energy intake constant, it could lead to an accumulation of body fat more easily (17, 7).

Avoiding weight gain after smoking cessation

Failure to gain noticeable weight can contribute to successful abstinence from smoking and reduce relapse rates. Physical activity could help avoid weight gain and make it easier for ex-smokers to abstain, but there are no studies on this with a longer duration, a larger study population and sufficient exercise intensity (39, 19 a, 25, cited in 13). Accompanying smoking cessation with cognitive behavioral therapy (31) and nutritional intervention (energy reduction) (4) can also help reduce the risk of weight gain and the relapse rate. Especially for heavy smokers, there are also pharmacological methods such as nicotine replacement therapy, dopamine and serotonin reuptake inhibitors, bupropion or rimonabant (not yet approved) for successful smoking cessation with a reduced risk of weight gain (9, 1).

As a content-related framework for nutritional advice for ex-smokers or people who want to quit smoking, the DGE recommends a conscious, balanced and possibly initially also energy-reduced mixed diet.


In Germany, an estimated 110,000 to 140,000 people die each year as a result of tobacco consumption (6). Calculations on the number of overweight / obese (BMI ≥25 kg / m2) attributable deaths showed that at least 1 in 13 deaths in the European Union can be linked to overweight / obesity. Converted into absolute figures, this was 63,700 deaths in Germany in 2001 (5), roughly half of the deaths attributable to tobacco consumption. Tobacco consumption is the single most significant health risk in industrialized countries today. In view of its high prevalence among the population and the high individual and social costs, the World Health Organization assumes that no other prevention strategy will achieve a comparable increase in life and quality of life can be considered through a sustained reduction in tobacco consumption (33). The positive health effects of quitting smoking affect every smoker, regardless of their previous smoking habits.

Compared to being overweight, smoking is by far the greater health risk. The health benefits of quitting outweigh the risk associated with weight gain with smoking cessation (e.g., 38, 35, 14). Smoking is not a means of regulating weight. The z. The risk of weight gain, sometimes classified as low, can be countered by accompanying smoking cessation with nutritional advice and increasing physical activity. Therefore, interventions to quit smoking, especially for heavy smokers, should also include weight control measures. Apart from that, primary prevention, i.e. avoiding smoking, especially with regard to children and adolescents, should come first.


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