Part Five – Brain Transmitters and Food Craving – The Role of Addiction in Weight Control

“Keep things as simple as possible not simpler”     – Albert Einstein

This isn’t rocket science but it is a little complicated. To really understand craving and other issues regarding eating and weight control you have to have a sense of how the brain works. Serotonin is one of the neurotransmitters that enables brain cells to communicate with one another. Brain transmitters are mostly made from amino acids (building blocks of protein). Some of them the body can make but some have to come from the proteins that we eat – another reason that our diets need to include adequate healthy protein.  In response to stimulation nerve cells release various transmitters. These transmitter are like keys that cross the synapses, spaces between nerves and other cells, which plug into receptors, like locks on other brain cells. Sometimes transmitters activate other cells.  While other times they plug up plug up the receptors preventing other transmitters from activating them.  

Serotonin, the oldest and most primitive brain transmitter, is found in single cell organisms. If you recall Maslow’s Hierarchy of Needs and Motivation, you know that the first level is our basic biologic needs. Of these biologic needs, air is the most urgent need, but water and food come in second and thrid.  Produced in the brain stem, serotonin’s primary responsibilities include maintaining homeostasis, or balance, of temperature, blood sugar and many physiologic systems. Serotonin raises when blood sugar increases, and this increase in serotonin stimulates satiety receptors and decreases craving for carbohydrates. Conversely, low serotonin or low serotonin activity due to certain medications working certain receptors leads to carbohydrate, or sugar, craving.  Don’t get between someone with carb cravings and sweets.  It’s dangerous, because the next level up on Maslow’s hierarchy has to do with safety and interaction with our environment.

Another neurotransmitter, norepinephrine (Noradrenaline) releases when changes occur, especially dangers in the environment. Norepinephrine activates our Cortisol stress system muscles for “fight or flight” while releasing adrenaline in the body. This has to do with avoiding danger and basic survival.  Adrenaline causes us to dump sugar from the liver into our blood stream, because sugar provides emergency fuel for muscle activity and is the only fuel for brain cells.  Muscles burn fat and carbohydrate (sugar), but the brain can only burn carbohydrate (sugar).  Norepinephrine increases arousal while decreasing appetite and libido, so it is not surprising that some appetite suppressants work by increasing norpinephrine levels.

Once our basic biological needs are met, and we feel safe, the next level up on Maslow’s Hierarchy is well being.  The next brain transmitter, dopamine drives us to pursue well being.  Every addictive substance increases dopamine.  Dopamine should not be confused with endorphins, which make up the pleasure system, but dopamine activates us and enables us to pursue the things that provide the feelings of pleasure and well being.  Experiments with male dogs found that their first experience with female dogs in heat or their first T-bone steak didn’t release dopamine but did stimulate the endorphin system. The next time they were given a T-bone steak or a female in heat, their dopamine release was off the chart. In other words, Mother Nature provided a brain system that learns where fun and well being are driving us to pursue this pleasure when future opportunity arises.  In another experiment, male rats had all their brain dopamine depleted. They were then given female rats in heat and an All-the-Cheese-You-Can-Eat buffet.  The rats acted completely normal, though, making passes at the females and chowing down on cheese. This meant dopamine wasn’t necessary to enjoy something pleasurable that’s put in your lap.  However, when a barrier was put up separating the food and females on one side and the males on the other,  the rats without the dopamine said, "Screw it, I can’t do it," and the normal rats with dopamine went right over the wall.  

Addiction is a process where the brain is hijacked by some substance(s) or activity and the individual loses control (dyscontrol).

The other primary symptom of addiction is denial to self and/or others.  A book title on alcoholism tells you everything you need to know about addiction: I’ll Quit Tomorrow. Other books, The Selfish Brain and The Craving Brain also paint the picture. The need for well being and the pursuit of pleasure can drive us to love and creativity or lead us down a path of self destruction. Losing a patient to an addiction is a painful and sobering experience. Mother Nature wants us to do things that are pleasurable like eat and have sex.  Though, not necessarily in that order and the survival of the human race depends upon these activities.  

People with ADHD need more stimulation, because their dopamine systems are not as naturally reactive.  People with addictions are low in dopamine in the area of the brain that is activated during pleasurable pursuits, the Nucleus Accumbens. One of the technological advances in the past decade enables us to look at not just brain structure but brain activity. Functional MRI’s are being used more often now because they don’t require radioactive material to be injected. PET scans using radioactive glucose were previously the most useful. Compare the PET scans of a normal individual on a normal day. Notice the dramatic difference between the normal brain and a chronic cocaine user. The cocaine user’s brain is like the rats with their dopamine systems depleted. They are useless unless pleasurable things are put in their lap. They need cocaine or some other powerful stimulant to turn on their brain.

The alcoholic brain is not as bad but still reflects low motivation and drive. The surprising finding is the low brain activity in the Nucleus Accumbens in the individual with obesity. What turns on their brain? The answer is food and especially carbohydrates.  Many experts now show that sugar can be as addictive as alcohol, speed, and cocaine and that addictions overlap to some degree. Periods of abstinence from addictive substances increases cravings, and the longer the abstinence the greater the craving. Sugar addiction increases response to amphetamines and visa versa. Some food addicts eat when bored, others eat when stressed.  Addiction occurs when you lose control meaning: You don’t control it, It controls you.  That’s why the first step in AA is admitting powerlessness, but change starts with awareness. The next step occurs with the decision to change and finally the hard part comes on the day you decide to start the process of change.  Fortunately there are things to help. See Part Six

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