what are harmful effects of tobacco The Many Dangers Use Harmful effects of smoking on

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PMID 18783507

One possible explanation is nicotine withdrawal.8 Although nicotine does not have an anorectic function and does not acutely reduce hunger and eating,9 it reduces food consumption and increases basal metabolic rate.8 9 In animal models, a decreased appetite was caused by binding of nicotine to the 4 subunit of nicotinic acetylcholine receptors in the hypothalamus, which stimulates the melanocortin-4 (MC-4) subunit of pro-opiomelanocortin neurons.10 Increased appetite after smoking cessation is a frequent and long-lasting withdrawal symptom11 and increased self-administration of palatable foods (ie, fatty meals and sweets) has been described after nicotine deprivation.12 Furthermore, smokers display an altered brain response to food in the hypothalamus, which is an area associated with long-term weight change in non-smokers.13 Additionally, delayed gastric emptying of solids has been explored in smokers14 15 and recent data described accelerated gastric motility after stopping smoking, and this may be involved in the temporary appetite increase.16 The role of gut microbiota modulation after smoking cessation has been introduced recently: profound shifts in the microbial composition and diversity were observed, and these changes seem to be similar to those already reported in obese compared with lean people, suggesting a potential pathogenetic link between weight gain and smoking cessation.17 Finally, the role of hereditary factors in weight changes after smoking cessation was suggested in a study with monozygotic and dizygotic twin quitters.18 19 PCWG is important