Why do smokers gain weight when they quit?

Nicotine increases metabolism and suppresses appetite. When someone quits smoking, their metabolism slows down, and they may experience increased appetite, leading to weight gain.

Some people may substitute food for cigarettes as a way to cope with cravings and withdrawal symptoms. 

When someone quits smoking the heightened sensory experience can lead to increased enjoyment of food and potentially overeating.

Smoking cessation can cause stress, anxiety, and mood swings, which may lead to emotional eating as a way to cope with these feelings.

Nicotine is a diuretic, meaning it causes the body to release water and salt. When someone quits smoking, their body may retain more water, leading to temporary weight gain.

Quitting smoking can disrupt the balance of hormones involved in metabolism and appetite regulation, potentially leading to weight gain.