It is up to you whether or not you eat. The hormones that regulate how much food we eat are insulin and leptin. It is so important that a lack of these hormones could lead to obesity, diabetes, or even Alzheimer's.
Most people associate insulin with the elderly who can't eat a slice of the delicious family dessert and must inject themselves every two or three days because their sugar levels are too high. What is insulin? But more importantly, why does so many people need insulin?
The main source of energy for humans is sugar from our diet (glucose). This glucose is responsible to move our muscles, make our organs function, and most importantly, feed our brain.
This is why it is so crucial that we ensure that our brain and organs get enough energy. Insulin is the answer. Insulin is a pancreatic hormone which opens a portal between the cells of our organs. This allows glucose from blood to flow into the portal and be used as energy.
What happens to the food we eat? What happens when we eat? Insulin travels through blood and reaches cells, opening a pathway for glucose to enter. In turn, blood glucose levels fall and glucose is converted into energy within cells. After a while we feel active.
Leptin is another hormone that's produced when we eat. Leptin is a type of adipokine. It is found in the adipocytes, which is where fat is stored. Yes, those hate handles that some people love so much have a first name and a last name: adipose tissues.
Leptin is produced by adipose tissues when we eat. It travels to the brain and tells us to stop eating. It is a satiating hormone which regulates fat reserves.
As you can see, insulin and leptin are not separate. Actually, insulin secreted when we eat favors leptin production. Leptin is a hormone that makes us feel less hungry because we are storing fats and stops more insulin being secreted. They make a great team.
In many situations, these intake control systems can be modified, such as smoking, sedentary lifestyles, genetic problems, overeating (and not just when we visit grandmother), and other factors.
All of these situations result in our bodies becoming exhausted and de-sensitized from the hormones. This is what happens when you put on strong perfume: it smells great at first, but then after 10 minutes it becomes almost unrecognizable.
The pancreas may stop producing insulin properly if we don't maintain a healthy lifestyle. Sometimes, our cells can stop responding to insulin even though they have normal or high levels. Then, we are called insulin resistant.
People with insulin resistance and those who don't produce it correctly have high blood sugar levels and a higher risk of developing diabetes. Some people with diabetes must take insulin to maintain stable blood sugar levels.
There is also Leptin resistance. It is common in obesity. People who are obese have higher levels of leptin. Curious, right? The problem is that long-term overeating causes brain damage that stops leptin giving the STOP signal. This makes it difficult to feel full, and then we stop eating. Genetically modified animal models that do not produce or respond to leptin have severe obesity.
Due to decades of lifestyle promotion, insulin resistance and leptin resistance have become increasingly serious health issues. They are often steps before the development of chronic diseases like diabetes or obesity. They may also be associated with unhealthy aging.
It has been suggested that insulin resistance and leptin resistance are linked to Alzheimer's disease. What should they do?
We have already said that glucose is the brain’s favorite food. Failures in insulin signaling were detected in Alzheimer's disease models in animals. This was particularly evident in the hippocampus region. This area, which is responsible for memory, is the first region to start to decline at the beginning.
We said insulin and leptin go hand-in-hand and, as we expected, leptin signaling also fails. Alzheimer's patients have been shown to be resistant to leptin. This has allowed us to identify insulin and leptin, which are crucial components of proper brain functioning.
It is now clear that insulin and leptin regulate what we eat to provide energy for our bodies and brains. They are also potential targets for therapeutic therapies, targets to direct therapies that can slow down or treat this neurodegenerative disease. To achieve this, as our Roman ancestors stated, a healthy man in corpore is healthy.
This article was selected as a finalist for the second edition of The Conversation Spain's youth disclosure contest. It has also been published in "The Conversation".