Serotonin release in the brain controls functions such as sleep onset, pain sensitivity, blood pressure regulation, and control of mood. Serotonin-releasing neurons are unique in that the amount of neurotransmitter they release is normally controlled by food intake: Carbohydrate consumption–acting via insulin secretion and the “plasma tryptophan ratio”–increases serotonin release dramatically (by enhancing the brain uptake of its precursor, tryptophan). Elevated serotonin causes significant mood enhancement and a generalized sense of contentedness. Patients learn to overeat carbohydrates (particularly snack foods and drinks, like soda, potato chips or pastries, which are rich in carbohydrates) to make themselves feel better.
Self-medication with carbohydrate rich foods as though they were drugs is a frequent cause of weight gain, and is often seen:
- In patients who become fat when exposed to stress
- In women with premenstrual syndrome (PMS)
- In patients with “winter depression” (Seasonal Affective Disorder)
- In patient’s who are experiencing chronic pain (ingestion analgesia)
- In people who are attempting to give up smoking. (Nicotine increases brain serotonin secretion; nicotine withdrawal has the opposite effect causing cravings.)
- As a consequence of chronic patterned carbohydrate consumption causing hardwired changes in neurons, such that there are cravings and feelings of withdrawal when carbohydrates are withheld
Carbohydrate load is so closely linked to addiction, that the Glycemic Index (GI) of specific carbohydrates correlates closely with their relative addictive strength and activates addiction neural pathways.
The take home message, carbohydrates are an addiction. Carbohydrate consumption promotes neurochemical changes, which reinforce additional carbohydrate consumption. There is now evidence that carbohydrate binging is akin to heroin addiction, with the cravings for carbohydrates reduced by opiates and more interestingly, carbohydrate cravings dramatically increased during opiate withdrawal. Unfortunately, carbohydrate addiction will definitely make you fat.