“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

Wow! That sounds like a copout - “genetic obesity”. But for many people it is reality. I have seen people who have more self-discipline than God (so I exaggerate a little), who have always maintained an ideal weight, and then they get on one of many types of medications and 3 months later they are 10 pounds overweight. That’s not a lack of discipline. That’s a change in brain function. When the “weight-o-stat” in the brain has been set higher, it can be next to impossible to avoid gaining weight.  There’s the constant push to eat more food, the wrong food, and there’s a decrease in metabolism even when you’re sleeping.  The power of the brain and the power of Mother Nature are hard to fight against.

One third of the U.S. population is obese (not just overweight). If you have one obese parent then the incidence of obesity goes up to 50%. If you have two obese parents your chances are over 70%. You might argue that this is due to learned habits regarding types of food, importance of food, learned attitudes about exercise, etc. But this increase in obesity risk is also found in people who had obese biologic parents and were adopted at birth.  The chance of being overweight is clearly influenced by genetics and not just the home you grow up in.  

Several years ago a study was done using identical twin adults. Most of them didn’t live together. Many were living in different cities than their twin sibling. Each person was asked to make no changes in their diet or activity level. The only thing they were to do different is drink a 1,000 calorie supplement at bedtime every night for 3 months. The results of the study were very striking. About one third of the individuals converted basically every extra calorie from their night beverage to extra body fat. So they added 7000 calories per week which meant they gained 2 pounds per week since 3500 calories equals a pound.  They did this for 13 weeks, which meant a total gain of 26 pounds. Another third of the individuals gained about 1/2 that amount, and the final third gained essentially no weight at all. Very interesting.

The most striking finding from this study was that the identical twins were always in the same group. Something in our genetic make-up helps determine what we do with extra calories or what adjustments we make in our overall intake or physical activity in response to an extra 1000 calories daily. I want to be clear that you are not born obese or genetically programmed to be fat. In fact, being born below normal weight and gaining more than the usual weight in the first few months actually increases the risk of obesity. Having the genetic predisposition for obesity, in which you are programmed to store a lot of extra energy, or fat, makes it a lot harder to be lean.  Just as some people are lean no matter what they eat or how physically inactive they are.  Don’t you just hate ‘em! Only Joking.  See Part Five

Many of the important systems in our body like sleep, body temperature, cortisol (stress hormone) and growth hormone go through a 24 hour cycle or Circadian Rhythm. How alert and effective we are is largely determined by where we are in our cycle. Where we are in the cycle is determined by when we are exposed to bright light (usually meaning outside during the day).

Light intensity is measured in lux and during the day the typical intensity is around 10,000 lux. Indoors in our offices the intensity is only about 500 lux or 1/20th that of the outdoors. Our homes are frequently even less. Light intensity is reduced by going through glass like in your car and by sunglasses. You don’t have to be in direct sunlight to get an adequate intensity level - it can be reflected light.

Bright light means, time to be productive, crank up the energy, and get motivated. Decreasing light means time to start shutting it down. Bright light raises serotonin. Low light decreases serotonin. Low serotonin increases carbohydrate craving. Studies are finding that during the shorter, less bright winter months our serotonin levels are lower (in all of us) and we are inclined to eat more carbs. People who are susceptible to certain kinds of depression will actually feel depressed when their serotonin levels are low. Eating carbs raises serotonin.

For many of us it’s not practical to be outside much, especially in the morning. If you go outside at noon and spend an hour or so you may be setting the sleep clock in your brain for 16 hours later, which would be 4 am.  This is probably one of the causes of insomnia for many people. However, there are lamps you can buy that provide adequate light intensity and though they are somewhat costly at about $150, they have come down some since originating. There is some debate as to whether you need full spectrum light including ultraviolet (tanning rays) and infrared (heat rays) or just intense bright (white) light. White light is probably all we need. These lights can be put by the bed to read the morning paper, or on our desks, and the one I have is about the size of a loaf of bread.

These lights may improve energy, mood, and sleep, and bright light can even decrease bingeing in some bulimics. They may replace or lower the dose of antidepressants for some people, and many antidepressants make it hard to lose weight since they can make the brain act as though they have genetic obesity.  Increasing bright light can help with weight control by increasing energy and metabolism and by reducing the need for meds that cause weight gain.

 See Part Four - Genetic Obesity