Smoking is a significant contributor to illnesses and deaths worldwide.¹ It is estimated that tobacco is responsible for more than 8 million deaths every year and may kill up to half of its users.² Smoking also has far-reaching effects on various aspects of metabolic health. Those who smoke tobacco are shown to have more than double the risk for developing metabolic syndrome when compared to non-smokers, a medical condition characterized by abdominal obesity, high blood glucose levels, high triglyceride levels, low high-density lipoprotein (HDL) cholesterol levels, and high blood pressure.^3–6 This article will focus primarily on the effects of smoking tobacco on weight, diabetes, and heart health.

 

How Does Smoking Affect Weight?

Smoking has shown to be associated with increased weight, increased waist circumference, and increased waist-to-hip ratio.¹ Studies have found that the relationship between smoking tobacco and waist circumference is dose-dependent, meaning that more years of smoking and greater number of cigarettes are associated with higher waist-to-hip ratio. It is thought that increased circulating cortisol (ie, stress hormone) levels and worsened insulin resistance from smoking can lead to increases in visceral fat mass as well as waist circumference.⁷ Although some studies show that smoking may lead to weight loss and that smoking cessation may lead to weight gain, there is clear evidence that smokers have higher body mass index and greater abdominal adiposity when compared to nonsmokers.

 

How Does Smoking Affect Risk of Diabetes? 

Smoking tobacco, even short-term, is known to be associated with the development of insulin resistance and hyperinsulinemia (ie, increased levels of insulin than normal).¹ Studies have demonstrated that smokers have almost double the risk of developing type 2 diabetes mellitus when compared to nonsmokers.^8,9 Among individuals already with diabetes, smoking is associated with increased risk of developing cardiovascular (ie, heart and blood-vessel related) diseases (CVD), microvascular complications, worse glycemic outcomes, and premature death.¹⁰ Tobacco use is known to stimulate the sympathetic nervous system (ie, nervous system that responds to stress) and increase circulating levels of stress hormones and growth hormones that can interfere with glucose uptake mediated by insulin.⁷

 

How Does Smoking Affect Heart Health? 

Smoking is also known to negatively affect heart health in various ways.¹ Studies have consistently shown that smoking disrupts blood lipid levels, increasing blood triglyceride levels while lowering high-density lipoprotein cholesterol levels.³ Nicotine found in tobacco promotes breakdown of fat and can increase levels of hormones that interfere with insulin action (eg, cortisol, catecholamine, growth hormone). This can promote lipolysis (ie, breakdown of fat) and increased levels of free fatty acid in the blood, leading to dyslipidemia (ie, imbalance of lipid levels) and disruption to pancreatic function. In addition, smoking is shown to increase levels of inflammatory markers and can further affect ways the body coagulates, or clots.¹ Acute increases in blood pressure and heart rate have also been seen with tobacco use, but no long-term differences in blood pressure have been noted from epidemiological studies.

 

What Should You Do?

Considering the overwhelming evidence surrounding the detrimental effect of smoking on health, all major organizations including the American Diabetes Association and the American Heart Association strongly recommend cessation of all tobacco products including e-cigarettes.^10,11 Studies have found that routine assessment of tobacco use and smoking cessation counseling are effective ways to encourage cessation. Use of pharmacotherapy can be effective when used in addition to counseling. Although some individuals may experience short-term weight gain after quitting smoking, studies have found that the benefits of smoking cessation, including improvements in CVD risk and metabolic parameters, greatly outweigh any drawbacks. E-cigarettes, which have gained recent popularity, are not recommended to be used to reduce smoking tobacco given the increasing evidence that e-cigarettes have similarly detrimental effects of health.