Quitting smoking and gaining weight

Geschatte leestijd: 5 minuten There is no more annoying reward for quitting smoking than a few extra kilos of body weight. Why do many people gain weight when they quit smoking? New research thinks it may have an answer.

Quitting Smoking and Weight Gain

As if quitting smoking isn’t difficult enough, there can also be a somewhat less positive consequence. Many former smokers complain that quitting smoking led to extra weight. Now, it’s always difficult to rely on anecdotal knowledge. After all, it’s hard to distinguish between quitting smoking and other factors that may have led to the extra weight. Sometimes it can be used as an easy excuse. However, research also shows a few annoying or pleasant correlations between smoking and weight, depending on your perspective. A few conclusions from such studies:

• Adult smokers weigh an average of 4 to 5 kilograms less than non-smokers [1,2]
• People who quit smoking gain between 3 and almost 9 kilograms in the 8 years after quitting. Non-smokers gain an average of about 2 kilograms in the same time [3,4]
• This increase in weight mainly occurs in the first 6 months after quitting (see fig 2) [5]

Smoking appears to slow down the weight gain associated with aging.

Increased Appetite after Quitting Smoking

Of course, this does not mean that you should start or continue smoking to achieve or maintain a healthy weight. Even considering this effect, the benefits of quitting smoking still far outweigh the disadvantages. For example, in terms of the risk of death. However, it does mean that part of the positive effect can be offset by the negative effects of a higher body weight.

Smoking and Satiety Hormone

Previous research has already shown that smoking can suppress appetite. One theory is that this is caused by the effect of nicotine on the ‘satiety hormone’ leptin [6]. But the effect on other hormones such as noradrenaline, dopamine, serotonin, and GABA can also play a role. The release of these chemicals influenced by the central nervous system affects the brain chemicals that suppress appetite and increase metabolism. The effect of nicotine on these hormones is complex. It can activate hormones that increase appetite and slow metabolism [7]. The direct effect is activation of systems that make you eat less and burn more. Chronic changes, however, show activation of systems that increase appetite and slow metabolism [8]. Moreover, smoking could be an alternative to eating, or more specifically, snacking. Personally, I noticed this especially when I quit smoking. A kind of oral fixation where I ate extra snacks as an alternative to smoking. Instead of smoking a cigarette, I would open a bag of candy. As long as my jaws were chewing.

Higher Fat Burning Due to Smoking

But as already mentioned, it’s not only appetite and the amount of food that is influenced by smoking. Also, how your body deals with food and fat mass is affected. So, smoking has multiple ways to inhibit weight gain. Nicotine increases thermogenesis in fat mass, among other things by increased burning of fats [9,10]. Smoking increases the amount of energy you expend over 24 hours by an average of 10% [11]. Ten percent can mean the difference between losing weight, maintaining weight, or gaining weight. The most recent research on the effects of smoking on weight provides some more insight into how the effect on increased fat burning is achieved [12]. The same proteins that regulate nicotine dependence in the brain may also regulate metabolism by acting directly on brown fat.

White Brown and Beige Fat in Brief

We’ve already devoted several articles to brown fat tissue. These fat cells, unlike white fat cells, are not aimed at storing fat, but at regulating temperature. When the body temperature drops, these cells increase fat burning to raise the temperature through thermogenesis. Babies use this to avoid hypothermia, but afterward, the amount of brown fat decreases. Cells in white fat tissue, however, can behave like brown fat under those circumstances and are called ‘beige fat’. Beige fat was discovered by the same researchers who now investigated the role of nicotine in this. Since the discovery, there has been much scientific interest in these fat cells. Successfully activating these beige fat cells could be an effective treatment for obesity.

Increased Burning by Brown Fat Due to Nicotine

Researchers at the University of Michigan Life Sciences Institute analyzed activated beige fat cells [12]. They discovered a molecule directly linked to thermogenesis in these fat cells, the protein CHRNA2 (cholinergic receptor nicotinic alpha 2). This is a type of receptor mainly known for regulating nicotine dependence in brain cells. CHRNA2 seems to function in human and mouse models but not in white fat tissue. This is an indication that this protein plays a role in metabolism. The research shows that the CHRNA2 receptor can be activated by both nicotine and acetylcholine produced in nearby immune cells. When the CHRNA2 receptor receives nicotine or acetylcholine, the beige fat cells are stimulated to start burning. “It is really cool to discover a selective pathway for beige fat, a new cell type — and even more exciting that this is conserved in humans,” said Wu, the study’s senior author and assistant professor of molecular and integrative physiology at the U-M Medical School. -Jun Wu, Life Sciences Institute

“The Benefits of Smoking”

Once again, it must be emphasized that smoking is not recommended as a means to lose weight. Only a specific effect of one of the countless harmful substances in cigarettes has been discovered. Even if you are now thinking of nicotine pills to avoid ingesting the other substances, this is not advisable. Nicotine itself also constricts blood vessels and thus increases the risk of cardiovascular diseases. The reason the researchers find this ‘cool’ is because it may bring them closer to finding the ‘on switch’ of beige fat. By mapping out the different ways beige fat is activated, pharmaceutical agents can be sought to achieve this. So, there’s no reason to pull the pro-smoking ads from the early part of the previous century out of the archives. It’s still just bad. But maybe there’s a future where knowledge about nicotine contributes to preventing obesity. It was good for something after all.

References

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12. Heejin Jun, Hui Yu, Jianke Gong, Juan Jiang, Xiaona Qiao, Eric Perkey, Dong-il Kim, Margo P. Emont, Alexander G. Zestos, Jung-Sun Cho, Jianfeng Liu, Robert T. Kennedy, Ivan Maillard, X. Z. Shawn Xu, Jun Wu. An immune-beige adipocyte communication via nicotinic acetylcholine receptor signaling. Nature Medicine, 2018;