While vape juice does contain a small number of calories, the act of vaping does not lead to any significant caloric intake, according to scientific understanding. The primary components of e-liquid, Propylene Glycol (PG) and Vegetable Glycerin (VG), are the source of these calories; however, the human body does not absorb them through inhalation.
An average estimate places the caloric content of vape juice at approximately 4 to 5 calories per milliliter. These calories stem from the chemical makeup of PG and VG, which are sugar alcohols. For instance, a standard 30ml bottle of e-liquid would technically contain around 120 to 150 calories.
However, the crucial distinction lies in the method of consumption. The digestive system is equipped to metabolize and absorb calories from food and drink. The respiratory system, through which vapor is inhaled, does not possess this function. When a user vapes, the e-liquid is heated into an aerosol that is drawn into the lungs. The lungs are designed for gas exchange (oxygen in, carbon dioxide out) and are not capable of processing and absorbing the caloric content of the inhaled vapor.
A minuscule and generally insignificant amount of calories might be ingested if some of the e-liquid condenses in the mouth and is subsequently swallowed. However, this amount is considered negligible in the context of a daily diet.
It is also important to note that nicotine, a common ingredient in many e-liquids, is a stimulant and does not contain any calories. Similarly, the flavorings used in vape juice contribute a minimal and generally inconsequential number of calories to the overall liquid.
In conclusion, while the liquid used in vapes is not calorie-free, the process of vaping prevents these calories from being absorbed by the body in any meaningful way. Therefore, vapers do not need to be concerned about caloric intake from their e-cigarettes.