As I told you in earlier posts, my father is a scientist. He enjoys reading neurobiological topics and talks a lot about them. When I told him about my blog, he suggested I should definitely write something about cravings and explain the reward system in the brain.
The following will be quite scientific but I hope it will help you to understand why your body reacts in a certain way to specific foods or other stimuli.
The neurons in our brain communicate with one another through the exchange of neurotransmitters (small molecules). These molecules fit into receptors on the surface of brain cells and lead to either stimulation or depression of the neuron’s activity. Whether the neuron gets activated or depressed depends on the kind of neurotransmitter. When that neuron is stimulated, the message is passed on from neuron to neuron by releasing neurotransmitters. This connection of bundles of nerve cells is called a “neural network”.
Tp operate properly, there needs to be a balance between the stimulating and depressing neurotransmitters in the brain. When this balance is destroyed, the brain has systems that detect the imbalance and try to correct them.
The Reward System
There are different systems in the brain and each of them involve different neural networks. The mesolimbic pathway is responsible for feeling pleasure. It is also called the “Reward System”. Furthermore, it is also involved in processes like learning and motivation.
The neurotransmitter this system uses the most is Dopamine. When Dopamine is released in the brain, the Reward System gets activated and the result is a feeling of happiness (euphoria).
The mesolimbic pathway is a detector of a rewarding stimulus. Its activation tells the brain that whatever stimulus causing the activation should be repeated. Memory cells in the brain save this experience, so it can be repeated in the future.
In fact, the mesolimbic pathway is one of the oldest systems in our brain. It played a primary role in survival for our ancestors.
You can see in the picture that this system involves many different parts of the brain. None of these parts work separately. They all work together to mediate an individual’s response to an environmental stimulus.
What releases Dopamine?
Drugs lead to a much higher activation in the Reward System than natural rewards do.
As I mentioned above, the reward that activated the mesolimbic pathway is saved in memory cells. Now, if the rewarding stimulus is repeated excessively, the balance of the neurotransmitters in the brain is destroyed.
Dopamine levels, thus the activating neurotransmitters, increase and the brain seeks a way to restore the balance. To do that, it alters the receptors on the surface of the neurons. This process is called tolerance.
As a result, to achieve the same feeling of excitement, more Dopamine needs to be released. This is also the process leading to addiction. Drugs by themselves create a very high release of Dopamine. Once the brain has adapted, a higher intake of drugs is necessary to get to the same Dopamine levels and the same feeling of euphoria.
If this is repeated over a long period, the brain again adapts by changing its neurons, their structure and function. This leads to behaviour like denial, irrationality and obsessive drug use in addicts.
Here comes the ice-cream
What I explained above about drugs applies to food as well. Especially processed foods that are high in sugar and trans-fats seem to trigger a very high Dopamine release. The same goes for alcohol as well.
High-glycemic foods (foods that stimulate a high insulin secretion) trigger not only a high release of Dopamine but also other neurotransmitters like serotonin and Endorphins. These are also called “natural opiates”, as they depress pain, stress and make us temporarily feel good. The brain saves this information and whenever you are stressed, in pain or sad, it wants you to consume those foods to restore the high levels of opiates it got used to.
The Science of Cravings
Foods with high levels of glucose are more frequently craved than foods with lower glucose, such as vegetables. The reason for this is the interaction of glucose with the reward system in the brain triggering the release of opiates and Dopamine.
When you are on a Weight Loss Diet, you cut out all sugary foods and many people even cut out carbohydrates and healthy fats. As a result, the reward system is not activated and the brain notices the lack of opiates. To restore the balance, hunger regulating systems in the brain are activated and Ghrelin (the hunger hormone) is released.
About craving specific types of foods
What you can do instead: Actually, chocolate, or rather raw cacao has many health benefits. It contains antioxidants, thus it can prevent cancer, it helps to dilate the vessels around the heart etc. You can have a piece of 80-99% chocolate when you feel very stressed in the evening. However, there are other ways to restore the balance of endorphins:
- Exercise: Feel that rush of happiness after completing your workout? That is the release of endorphins, leaving you less stressed and happy.
This has to do with the regulation of the sodium potassium household and water resources in your body. If you are dehydrated, specific hormones are released in the brain that make you want to eat something salty. The additional salt will help to flush more water into the cells. So, stay hydrated!
These are mostly craved when energy is low. Carbohydrates are our body’s main source of energy, so it is common sense the body wants to restore its Glycogen stores after exercise or at the end of the day. It is important to choose the right kind of Carbohydrates to fuel your body and prevent a high spike of insulin, which results in fat gain.
Additional Notes to consider:
If you are constantly craving food, it might be an indicator of a disease too. Examples are Diabetes and heart disease. Make sure to consult your doctor about this!
This is not a complete list of foods you could crave. It is just meant as an example, as I would like you to understand why you experience those cravings. If you are iron deficient, you can crave meat etc.
I hope this post helps you to understand you body’s signals and take control over them. The next time you are craving something sugary, you know what lacks in your brain, so instead of eating candy, go exercise or take a nap or have a nice meal with wholesome foods nourishing your body.
I hope you enjoyed reading! I had a lot of fun writing this and going through my neurology books again 🙂
Wish you all a wonderful day!
“Physiologie des Menschen (Human Physiology)” – Schmidt, Lang, Heckmann – 31. edition0