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Addictive brain function found in overeaters

Scientists have noticed for several decades that the brains of overeaters show altered functioning similar to the brains of drug addicts. [26, 27] These observations are based on a growing body of research literature generated from brain imaging studies designed to understand addictions as well as overeating. This research is important because it supports the definition of overeating as an addiction. 

The addiction-like changes found in the brains of overeaters are as follows: 

1. Over-active addictive pathways. These pathways are also known as the pleasure or craving pathways and include serotonin, dopamine, opiate, endorphin, and endocannabinoid. In overeaters, these pathways over-secrete craving neurotransmitters. [28] This 'flooding' of addictive neurotransmitters appears to produce intense cravings that are associated with loss of control. 

2. Sensitivity to triggers. In overeaters, very slight stimulation can trigger the overproduction of carving neurotransmitters. Researchers have seen that just thinking about a processed food product can produce a flooding of craving neurotransmitters. [29]

3. Conditioned, learned, or Pavlovian responses. The craving response of overeaters, like those of addicts, can be subject to conditioning. [28] Just as Pavlov conditioned the saliva glands of dogs to activate at the ringing of a bell without the presence of food, addictive neuro-pathways can also be conditioned to activate even when processed foods are not present. This means that a place, person, thing, even a time associated with the consumption of processed foods can trigger cravings without the presence of processed foods. 

4. Non-functioning cognitive centers. During a flooding of addictive craving neurotransmitters, the decision-making, memory and learning centers in the brain cease to function. [27] This may 'explain' many of the behaviors seen in the APA's addiction diagnostic criteria. At the moment of cravings, people are not able to remember consequences nor make good decisions. 

5. Non-functioning inhibition center. The flooding has also been observed to coincide with 'shut-down' of the inhibition center. [30] This is interpreted as a loss of control, and may contribute to the unintended use described in the APA's addiction diagnostic criteria. 

6. Down-regulated receptor fields. In order for the pleasure neurotransmitter to complete its circuit, it must 'hit' or 'dock-on' a transmitter receptor. In addicts and overeaters, these receptor fields are down-regulated or 'shut-down'. [31] The theory is that as over-use and overexposure to stimulation create neurotransmitters that bombard these receptors, they down-regulate. The person then increases consumption in an attempt to reestablish the level of pleasurable feeling they once had when the receptors were open. This may explain the phenomenon of tolerance or progressive use. 

7. Activation by stress. The addictive pathways are activated by stress in overeaters. [32]