How Does Your Body Build Tolerance Against Substances
There was a very interesting question on Reddit on how the body builds tolerance against substances. Here was the answer:
It can be a very complex process and is different for every chemical, but we can describe the general trend of whats going on when a body develops tolerance.
Firstly, the body developing tolerance is different from the brain developing tolerance, but they are still closely dependent on each other. The body being tolerant is physical tolerance. This happens because your body can metabolize the chemical more quickly. A body might be able to drink lots of alcohol because it has alcohol tolerance. It has more liver enzymes to metabolize the alcohol before it can even get in the blood stream, so less alcohol can go to the brain. The body can develop some degree of physical tolerance to most drugs, psychoactive or not.
Then there’s psychological tolerance. Once the chemical passes into the blood stream, and only if it is the correct size/shape, it can pass the blood brain barrier. In the brain it causes psychoactive effects by bumping into and activating a variety of different neurotransmitter receptors, or by binding to allosteric modulation sites, or by preventing reuptake of a neurotransmitter, or by causing the nerve to dump all of its neurotransmitters into the synapse, etc… Very complex chemical cascades ensue. Repeated exposure will cause the brain to adapt by producing more/less neurotransmitters, producing more/less receptors, pulling receptors in/out of the cell membrane, turning receptors on/off, and of course growing new (and possibly unwanted if the drug is addictive) interconnections between neurons. This makes the brain “better” at doing brain things while its surrounded by the drug, which makes its worse at doing brain things when no drug is present. Only psychoactive drugs produce psychological tolerance because only they can pass the blood-brain barrier and act on the nervous system.
Both of these tolerance processes are really specific cases of the body maintaining homeostasis. Anytime a body takes in any exogenous substance, it responds by trying to 1.) metabolize the chemical, absorbing whatever it can in quantities that are favorable to 2.) restore normal functioning business-as-usual as soon as is necessary. This is homeostasis. It happens when you take in any chemical. Not just drugs, even food, and (to a much smaller degree) water and oxygen/CO2. Our bodies develop tolerance because they are always trying to restore business-as-usual. If business-as-usual involves a foreign chemical in your blood stream, the body needs to adapt to tolerate this chemical imbalance. Tolerance is proof of your body maintaining homeostasis as best it can.
That very same answer can be applied to how your body builds tolerance against Kratom and Phenibut.
Tolerance From Kratom And Phenibut Builds Up Really Fast