Will long-term smoking cause obesity?

The relationship between long-term smoking and obesity is complicated. Smoking itself does not directly cause obesity, but it may affect body weight through indirect factors such as metabolic changes and appetite regulation. The main influencing factors include the suppression of metabolic rate by nicotine, rebound appetite after quitting smoking, changes in eating habits, reduced exercise, and fluctuations in hormone levels.

1. Changes in metabolic rate:

Nicotine will temporarily increase the basal metabolic rate, and smokers' daily caloric consumption is about 5%-10% higher than that of non-smokers. However, long-term smoking may damage mitochondrial function and lead to a decrease in metabolic efficiency. After quitting smoking, the metabolic rate returns to normal levels. If the diet is not adjusted, a caloric surplus will easily occur.

2. Abnormal appetite regulation:

Nicotine inhibits hunger by acting on the α3β4 nicotine receptors in the hypothalamus. The average daily caloric intake of smokers is 200-300 calories less than that of non-smokers. After quitting smoking, the sense of taste recovers and appetite increases. Some people will develop compensatory eating behaviors, especially increased intake of high-sugar and high-fat foods.

3. Changes in fat distribution:

Smoking increases cortisol levels, which can lead to visceral fat accumulation. Research shows that those who smoke more than 20 cigarettes a day increase their waist-to-hip ratio by an average of 0.03. This type of central obesity is closely related to insulin resistance. Heavy metals such as cadmium in smoke may also interfere with fat cell differentiation.

4. Decreased athletic ability:

Long-term smokers' maximum oxygen uptake VO2max is reduced by 15%-20%, and their cardiopulmonary function is weakened, resulting in insufficient exercise tolerance. The carbon monoxide in smoke reduces the oxygen-carrying capacity of hemoglobin and intensifies oxidative stress in muscles. These factors combine to reduce exercise consumption.

5. Effects of withdrawal reactions:

After quitting smoking, dopamine secretion is temporarily insufficient, and some people obtain compensatory satisfaction through eating. The feeling of emptiness in the mouth prompts an increase in the frequency of snack intake. Studies have found that quitters consume an average of 350 more calories per day in the first three months, 50% of which comes from sugary drinks.

For smokers, it is recommended to quit smoking in a step-by-step manner to avoid sudden weight gain. During quitting, you can increase dietary fiber intake to maintain a feeling of fullness, and choose low-glycemic index foods to stabilize blood sugar. 150 minutes of moderate-intensity aerobic exercise every week, such as brisk walking, swimming, etc., can help regulate metabolism. Pay attention to monitoring changes in waist circumference. Men should control it below 90 cm, and women should not exceed 85 cm. If abnormal weight gain persists, it is recommended to consult a nutrition department for a personalized metabolic assessment.