“I don't stop smoking because I'm afraid I'll gain weight.” If this is the alibi of many people, science will dismantle it. Or better. Although it may be true that among the concerns for those who have smoked there is also that of control of extra pounds and that sometimes it can happen that you gain weight after giving up cigarettes, it is on the “quality” front of the fat that accumulates for smokers that the situation is particularly dangerous. Even if you may appear fit.
In fact, research published in Addiction shows that those who start smoking, like those who continue with cigarettes, could have a higher risk of accumulating visceral fat. This is dangerous adipose tissue on the metabolic front: excess fat in the abdomen is associated with a higher risk of developing diabetes, vascular disease and other health problems. And unfortunately the fat inside the abdomen can be there even with a flat stomach.
The situation appears particularly important also on the basis of the numbers, which during the pandemic have seen a worrying trend in the number of smokers. In Italy, according to the data from the “Report on smoking in Italy” of the Istituto Superiore di Sanità released in 2022, there is still a lot of smoking. There would be 12.4 million smokers in Italy (24.2% of the population) and 7.7 million ex-smokers (14.9%). This latter share must rise, as well as obviously being accompanied by a decrease in the onset of the smoking habit.
What the research shows
The study was conducted by scientists from the Center for Metabolic Research at the University of Copenhagen coordinated by Germán D. Carrasquilla. And it was created by combining with a particular statistical analysis (it's called Mendelian randomization) the results of several genetic studies to look for causal relationships between an exposure (in this case, smoking) and the outcome (increased abdominal fat). From the investigation, obviously taking into account factors that can influence the formation of adipose tissue, it clearly emerges that starting to smoke and continuing to do so could cause an increase in fat within the abdomen. This is demonstrated in particular by the waist-hip measurement. But it's not enough. The quality of fat also appears to be the most likely to increase, while there appear to be no particular effects on the potentially less dangerous adipose tissue, the subcutaneous one. The influence of smoking on abdominal adipose tissuetherefore, seems to occur without the influence of factors such as socioeconomic status, alcohol consumption or other elements.
In short: researchers have determined that excess abdominal fat in smokers it is predominantly visceral origin.
Why abdominal fat is dangerous
The adipocyte, i.e. the adipose cell, if in excess inside the abdomen can promote a series of negative processes on the endocrine system and metabolism.
First becomes more difficult to control weight. In the presence of high quantities of intra-abdominal fat, the normal food intake control mechanism is altered, mediated mainly by leptin. This substance does not inhibit the appetite as it should and therefore further food intake is encouraged, with a constant worsening of the metabolic situation. It can also increase the production of free fatty acids, which are produced by excess fat cells. The increase in these lipid components in the blood contributes to increasing the triglyceride and cholesterol values LDL in the blood with progressive increase on total cardiovascular risk.
Not only. The excess free fatty acids “compete” with glucose and are used in its place by the muscles, so an increase in blood sugar, that is, glucose in the blood. The increase in blood glucose leads to the response from the pancreaswhich increases the production of insulin. Not only that: in these circumstances the elimination of excess insulin by the liver is also not effective, so an increase in insulin in the blood occurs in the presence of hyperglycemia.
Finally, theexcess fat promotes hypertension due to the increase in the effect of adrenaline on small vessels, which are therefore “narrower” (vasoconstriction), and due to the increase in cortisol activity mediated by the cells. This stress hormone actually increases the synthesis of adrenaline.
White fat cells, because they are more dangerous
Fat cells are of two types: those whitewhich represent the vast majority of the fat present in the body, and those brunettes. The latter retain the fat molecules within them in the form of small droplets independent of each other, and therefore more easily eliminated than the “large” and single drop of lipids that forms in the white cells. Not only. Brown adipose tissue would have a greater ability to control body weight because its primary task is the production of heat. Brown adipocytes are present in high quantities in newborns, while they are almost absent in adults. There deficiency of brown cells and their progressive replacement with white adipose tissue could be implicated in the genesis of the many problems linked to visceral obesity. In fact, brown cells ensure a high energy consumption, especially after having consumed foods very rich in lipids, and therefore very caloric, almost as if they were a sort of internal weight “regulator”. The more you eat, therefore, the more energy is produced in order to maintain normal metabolic balance in the body.
The white cellswhich progressively and autonomously replace the brown ones as the years pass because the former do not have to perform any heat “production” function in our environmental conditions, they are instead real “reservoirs” of fat.
In short: brown cells still tend to consume excess energy, when obviously you don't exaggerate too much with your diet, while white cells retain most of the lipids that come from food, if you don't make physical efforts that justify the need for the body to “draw” on these reserves.
