Our bodies are incredibly complex chemical factories. Medical science understands only a few of the chemical reactions that continually take place. There are dozens of neurotransmitters thought to be involved in mood, cravings, appetite, and eating.

Biochemical reactions form a system of interactions that regulate and balance body processes. When a certain chemical exceeds the normal range, the body releases another substance that may release another chemical that in turn inhibits production of the first one.

The body reacts to any imbalance with an attempt to restore that balance. These processes affect your physiology, your biochemistry, your psychology, and ultimately, your behavior.

Addiction always involves excess. Most of these excesses upset our biochemical balance. If we perceive that imbalance as increasing pleasure or reducing pain, we tend to repeat it. The body adapts, in its attempt to restore balance, and creates a tolerance. We eventually increase the excess to get the desired effect, and addiction progresses.


Many drugs, including alcohol, depress bodily functions and relax mood. This suppresses anxiety, pain, fear, and many other emotions that may be viewed as unpleasant. The body detects the artificial suppression of these functions, and begins to increase the arousal signals. As these “negative” sensations build, an addict will naturally tend to reach for the drug that gave relief before.


Other drugs suppress the parasympathetic nervous system. This is the part of the central nervous system that signals the body to slow down, relax, enjoy, or sleep. So the result is arousal, being “stimulated.” Again, the body detects the imbalance, and increases the parasympathetic signals. The addict takes more stimulants, becomes “wired,” and eventually crashes.


Drugs like LSD and marijuana distort perceptions and the thinking process. Depending on whether you-like the feelings that accompany these distortions, they may or may not be pleasurable. Because these drugs tend to have strange biochemical effects, it is difficult to categorize them as “upper” or “downer” drugs. But the neurochemistry of fantasy is powerful, and many fantasy addicts show a clear progression to stronger fantasy and other addictive substances or activities.

Blood Sugar Levels

We usually perceive an increase in blood sugar level as a good feeling. If the increase is very high or very rapid, the body reacts to reduce the blood sugar level, and an addictive cycle can result. This happens to many addicts, whether or not they acknowledge eating addiction. A stereotypical representation of an alcoholic in AA includes the image of them having a little coffee with their sugar.

Insulin, Tryptophan, Serotonin

Rapid increase of blood sugar can produce an excess of insulin released into the blood. The insulin forces glucose and large neutral amino acids (the building blocks of protein) into body tissues, like muscle. The amino acid tryptophan is relatively unaffected by this action of insulin. The lowered competition from these other amino acids allows tryptophan to cross the blood-brain barrier into the brain, where it becomes serotonin, a neurotransmitter that can act as a natural tranquilizer.

Protein, Tyrosine, Norepinephrine

An excess of protein produces imbalances too. For example, the amino acid tyrosine, one of the building blocks of protein, produces the neurotransmitter norepinephrine in the brain. An excess of norepinephrine has a stimulant effect in many neurochemical circuits.

Exercise & Endorphins

Rigorous exercise that lasts more than about thirty minutes triggers the body’s release of endorphins, which are natural analgesics (painkillers).


The low blood sugar production of ketone bodies and other biochemical changesthat take place in starvation can produce a high that resembles amphetamine use.


Less is known about the specific role of fats, in the biochemistry of eating addiction. Yet the prominence of bingeing on fats, especially in combination with sugar or salt, suggests a powerful addictive mechanism.


There is promising research showing that leptin, the satiety hormone plays a part in eating addiction and obesity. Normally, the body produces leptin to inhibit appetite. Obese people show resistance to leptin, something like the resistance to insulin in type 2 diabetes. This fits into the addiction model to help explain eating addiction. Wikipedia: Leptin


Deprivation, especially after the development of a tolerance for a biochemical imbalance, produces cravings and stimulates obsession and compulsive behavior.

Imbalance In addiction, we train our bodies to expect excess as the norm. If these excess (euphoric) levels are not regularly met, dysphoria (bad feelings) results. Addicts’ bodies have learned this expectation so well that neurochemical imbalances feel “right,” and moderation feels “flat” or “depressing.” These perceptions and attitudes encourage relapse.

Progression Tolerance to addictive imbalances increases over time, requiring stronger imbalances to produce the desired euphoric effect. This means that the dysphoria and other results of withdrawal also increase over time.


We have no evidence that the biochemical dynamics of addiction decrease in recovery. In fact, AA experience suggests that something involved with physiological addiction continues to increase even during abstinence. Perhaps it has to do with the affected organs getting older and adaptation less efficient.

Still, in good recovery the emotional, mental, and spiritual aspects of recovery counterbalance the biochemistry, decreasing the probability of relapse as time goes on.

In balance — HALT In the light of the biochemical basis for addiction, it is important for recovering addicts to avoid strong biochemical imbalances, particularly those that affect mood. For years AA has recognized the danger of becoming too hungry, angry, lonely, or tired (HALT).

Functioning as intended Biochemical imbalances usually wind up degrading the body’s ability to perform. If, as the Big Book suggests, your task as a recovering human being is to be of maximum service to God and your fellows, then you will want to take care of your body, your emotions, your mind, and your soul.

Biochemistry, see also: Addiction, Allergies, Craving, Fats, Metabolism, Moodifiers, Neurotransmitters, Nutrition, Physical aspects, Sugar, Tolerance, Withdrawal.

Updated 7 Sep 2015

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Addictionary 2 by Jan & Judy Wilson

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