Does Smoking Break Your Intermittent Fast?

Dieser Artikel basiert auf wissenschaftlichen Studien

Intermittent Fasting | Break a Fast | Blood Work | Smoking | Vaping

Besides chewing gum and drinking, e.g., coffee, smoking raises crucial questions about intermittent fasting, especially if you’re starting.

This article examines what kind of smoking can break your intermittent fast, from cigarettes to vaping to marijuana.

What Is Intermittent Fasting?

Intermittent fasting involves eating only within a particular time. You spent the rest of the day fasting. 

Although there are various forms of this intermittent fasting, the most popular method is fasting for 16 hours. 

Therefore, in 16/8 intermittent fasting, you may only eat during a window of 8 hours a day, such as from 12:00 to 20:00. 

To assess whether smoking can break a fast, we must find out for what purpose we want to fast in the first place. 

In short, there are two primary goals of intermittent fasting: 

  • Weight Loss 
  • Autophagy

In this regard, our body’s hormonal balance is vital for both goals. Since it is the essential storage hormone of our body, insulin is at the center of our considerations. 

Weight Loss

People can successfully lose weight with intermittent fasting since it’s the best way to lower insulin levels. 

Insulin is responsible for signaling cells to take up glucose from the bloodstream and store excess energy as fat or glycogen. 

Accordingly, using insulin levels, researchers can predict 75% of the gain and loss in overweight people (Kong et al. 20131). 

In addition, insulin prevents the breakdown of body fat (Meijssen et al. 20012). 

The 16-hour fasting window stops nutrient intake, lowers insulin levels, and thus ends the body’s storage mode. 

Therefore, the body can deplete carbohydrate (glycogen) stores. Once they are empty, it taps into body fat for energy instead. 

This mechanism is probably the essential goal of intermittent fasting for most people.

Consequently, our bodies build up fat reserves during abundance to draw on this body fat during food scarcity. 

We gain weight because we now eat around the clock regardless of the season. In contrast, intermittent fasting restores the natural balance between eating and fasting. 

Accordingly, fasting corrects the hormonal imbalance that causes obesity (Lustig 20013). 


The second primary driver of the health benefits of fasting is autophagy

As soon as food becomes scarce, this intracellular recycling system starts breaking down broken cellular parts and injecting toxins into the body. 

Therefore, it prevents precisely those modern diseases that plague us today, such as cancer, diabetes, cardiovascular diseases, and Alzheimer’s. 

Because the health benefits of autophagy are groundbreaking, it was rewarded with the Nobel Prize for Medicine (Levine et al. 20174). 

But how is autophagy turned on and off? 

To this end, three primary nutrient sensors exist in our bodies: 

  • Insulin: Sensitive to carbohydrates and proteins
  • mTOR: Sensitive to proteins 
  • AMPK: Sensitive to lack of energy in cells 

AMPK reacts when cells are supplied with energy – regardless of the macronutrient. As a result, in addition to carbohydrates and proteins, fat also prevents autophagy. 

Nevertheless, AMPK and insulin activate mTOR, which is why this enzyme, essential for growth, is called the primary nutrient sensor. 

As soon as you eat, mTOR determines nutrient availability and overrides autophagy. 

However, if the nutrient supply is prolonged, cells respond sustainably by recycling defective cell parts for energy. 

Since the storage hormone insulin is essential for autophagy and weight loss, the recycling mechanism sets the bar for fasting. 

If you disable autophagy, you break the fast. 

Does smoking a cigarette break your fast?

Can You Smoke When Intermittent Fasting?

To elicit whether smoke breaks the intermittent fast, we must determine whether it can increase blood sugar or insulin levels.

Moreover, it is essential to our question whether smoking can supply the body with protein or fat in addition to carbohydrates. 

Can You Smoke When Fasting for Blood Work?

Smoking does not significantly affect a blood test.

Many people – including some doctors – assume that fasting blood sugar rises when a person smokes. If this theory is true, smoking could break the fast since a blood sugar increase stimulates insulin secretion. 

Consequently, smoking would have affected a blood glucose test. For example, this effect on the blood test could lead to an incorrect diagnosis of diabetes. 

For this reason, researchers conducted a study on ten diabetics and 18 non-diabetics, with all participants smoking regularly. 

They found that neither fasting blood glucose nor response to oral glucose consumption was affected by smoking. 

Thus, this study found that cigarette smoking did not affect carbohydrate metabolism in smokers. 

Also, according to their conclusion, smoking cannot significantly distort the result of an oral glucose tolerance test (Walsh et al. 19775). 

The bottom line is that a smoker who fasts for a blood test can smoke during that time without confounding the test. 

However, breaking the fast is not determined by blood sugar but by the insulin response that sugar causes. 

Does Smoking Break Your Fast?

Only menthol cigarettes and cigars can break the fast.

Many overlook that insulin levels can increase even without glucose intake. For example, this happens with sweeteners like aspartame, acesulfame potassium, or stevia. 

Our study, which looked at fasting blood glucose, also inspected insulin levels. Thus, scientists found that smoking without oral glucose intake could not significantly affect non-diabetics (Walsh et al. 19776). 

Furthermore, other studies have examined smoking and insulin – specifically, insulin resistance. 

This condition means that cells no longer respond fully to the hormone. As a result, although the messenger can signal glucose uptake, the cells respond only to a limited extent. 

Therefore, they take up less glucose from the bloodstream. Thus, the body must produce more insulin, while excess glucose is stored as body fat. 

In the long run, obesity, diabetes, metabolic syndrome, Alzheimer’s, or Parkinson’s disease result. 

Moreover, a study of healthy smokers found that smoking, but not sniffing tobacco, causes acute insulin resistance. 

In addition, the researchers concluded that smoking promotes the development of chronic insulin resistance and cardiovascular disease (Attvall et al. 19937). 

A recent study supports this judgment by identifying smoking as a significant factor in insulin resistance, hyperinsulinemia, and type 2 diabetes (Haj Mouhamed et al. 20168; Sliwinska-Mosson et al. 20179). 

Even though smoking affects how our body uses insulin, it may not increase insulin levels. 

However, a recent U.S. study found that sugar is the #1 or #2 additive on the ingredient list for most cigarette brands. Among these, menthol cigarettes fared poorly (Seidenberg et al. 201810).

Moreover, some cigarette brands also cure their tobacco in corn syrup. 

For these reasons, most commercial cigarettes can interrupt intermittent fasting, especially if you smoke frequently.

Does Vaping Break Your Fast?

Vaporizing nicotine works in the same way as smoking tobacco. Therefore, it does not trigger an insulin response and will not break the fast.  

However, people rarely vape without distinctive flavors, which you might identify by the sweet smell. For example, these are elaborate flavors like cherry caramel or banana papaya. 

Of course, if you add flavors with added sugar to the nicotine, we get the same result as most menthol cigarettes. 

Accordingly, vaping with added flavors can technically break your fast, which it definitely will if you consume a lot. 

Therefore, it’s better to use the ingredients of your products twice before using them during intermittent fasting. 

Does Smoking During Fasting Suppress Appetite?

When you start intermittent fasting, new, more extended periods of fasting can be challenging at first. 

So why wouldn’t you turn to tobacco while doing so – smoking is known to suppress hunger, right? 

Several researchers have already investigated this question. But the startling result is always the same: smoking has no acute effect on hunger, caloric intake, or macronutrient intake (Perkins et al. 199411).

Consequently, scientists conclude that other mechanisms must be responsible for the lower weight of smokers (Perkins et al. 199212). 

One of the surprising effects of smoking that could be responsible for this is that it affects our heartbeat. Thus, it increases the risk of cardiovascular disease on the one hand and the basal metabolic rate on the other. 

Accordingly, a study has found that smoking acutely increases blood pressure and pulse rate in smokers and non-smokers (Frati et al. 199613). 

The basal metabolic rate accounts for about 95% of daily energy expenditure in an average person. That includes essential organ and body functions necessary for survival: 

  • Respiration 
  • Body temperature 
  • Fluid balance 
  • Acid-base balance 
  • Heartbeat 
  • Brain function 
  • Liver function 
  • Kidney function 

Thus, the increased energy expenditure due to increased cardiovascular stress could cause lower body weight in smokers. For this reason, people might also gain weight after they quit smoking, which lowers their basal metabolic rate. 

Last, a standard theory is that smoking might curb appetite due to increased dopamine release (Brody et al. 200914). 

Since the neurotransmitter provides the same reward effect as sweets in the brain, it could reduce cravings. However, this theory has not been proven true in studies to date (Perkins et al. 199415).

Smoking marijuana does not break an intermittent fast

Does Smoking Marijuana Break Your Fast?

Since doctors prescribe medical marijuana to people who suffer from loss of appetite, it will make you hungry instead of suppressing your appetite. 

So if you have trouble sticking with intermittent fasting due to hunger, the green herb is a terrible idea. 

However, we’re interested in whether smoking cannabis breaks the fast. 

A study examined the fasting blood glucose and insulin levels of 4657 participants and participants after a 9-hour fast for over five years. 

It found insulin levels in people who smoked marijuana were, on average, 16% lower than in others. 

But that’s not all: these individuals also had a 17% lower risk of developing insulin resistance and a narrower waist circumference (Penner et al. 201316). 

Therefore, unlike tobacco, smoking cannabis lowers insulin levels in the long term and increases insulin sensitivity. 

For this reason, marijuana could even positively affect people with diabetes (Alpert 201317).

Furthermore, it does not break the fast more than tobacco or nicotine. Accordingly, smoking marijuana cannot break the intermittent fast unless combined with tobacco using added sugar. 

Nevertheless, I do not advise you to use marijuana or combine it with intermittent fasting. Instead, I am simply preparing facts based on recent studies. 

The Bottom Line

While smoking natural tobacco and cannabis does not break the fast, it may differ from most cigarette brands and vapor. 

This effect is due to added sugars and is underestimated by most people who smoke regularly (Seidenberg et al. 201918). 

Therefore, if you already smoke during intermittent fasting, try to switch to rolled cigarettes with natural tobacco, no added sugar, and fewer chemicals. 

Not only will this make it less likely that you might break your fast, but it could also make conventional cigarettes healthier. 

Although smoking natural tobacco is thus possible during intermittent fasting, it could be more harmful during prolonged fasting. 

After all, the body is supposed to detoxify itself through autophagy over days, but you constantly supply new toxins. Accordingly, one cannot rule out serious side effects when smoking during extended fasting. 

According to studies, smoking cannot inhibit hunger or affect eating behavior, so it is not beneficial to smoke during intermittent fasting.

Frequently Asked Questions (FAQ)

Can I smoke after breaking my fast?

Although it is not generally healthy, you may smoke after breaking your fast. However, if you fasted for more than 72 hours, it might be advisable to wait 2-3 hours before smoking.

Does nicotine affect fasting?

While cigarettes with added sugars can, nicotine itself does not affect fasting.

Does inhaling break your fast?

It depends on what you inhale. While a natural one doesn’t, tobacco with added sugar and flavored vape juice might break your fast.

Can I vape while fasting?

Vaping may not break a fast, but most flavors will due to added sugar.



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Mag. Stephan Lederer, MSc.

Mag. Stephan Lederer, MSc. is an author and blogger from Austria who writes in-depth content about health and nutrition. His book series on Interval Fasting landed #1 on the bestseller list in the German Amazon marketplace in 15 categories.

Stephan is a true man of science, having earned multiple diplomas and master's degrees in various fields. He has made it his mission to bridge the gap between conventional wisdom and scientific knowledge. He precisely reviews the content and sources of this blog for currency and accuracy.

Click on the links above to visit his author and about me pages.

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