Obesity & Leptin Hormone; Leptin Resistance
Obesity is one of the biggest health problems of our times. Obesity, which can now be even seen very frequently in childhood, is threatening human generation in a serious manner. Together with many vital diseases it caused preventing and curing obesity have become the topic that is being studied the most in medicine.
There are many scientific studies at this point, in the triad of the endocrine system, exercise, and nutrition. But, life and nutritional habits of individuals, genetic factors, and the diversity of sociocultural differences make it more difficult to achieve success. But, coming up with a roadmap in its basic outlines is very important and necessary for the health professionals who are working on this topic. The different studies and findings of scientists which have been going on for many years are shedding light on us at this point. For me, it is a must to be tracking innovations under the light of science.
Of course, it is very important to raise awareness of this in NGO's, governments, parents and almost the entire community for the solving and preventing the problem before it even starts.
Some important headlines about Obesity.
World Health Organization(WHO) describes obesity as; abnormal or excessive fat accumulation in the adipose tissues in a health-disturbing measure. Obesity is a disease which forms with the increase of fat ratio in the body alongside with endocrine and metabolic variances.
• Childhood obesity plays a role in developments of diabetes, hypertension, hyperlipidemia, atherosclerosis, respiratory system diseases, orthopedic problems and psychosocial disorders in older ages.
• The frequency of obesity shows itself in every age group. Conducted research shows that there are around 15-20% of people are obese in middle-aged Europian population
• In USA only, obesity is responsible for the deaths of 300000 premature babies every year.
• Also, obesity is a very vital risk factor for cancer development (Nia and Her friends, 2009). It is predicted that Body mass index of 1.5 billion people in the world is 25 or more. And it is thought that around 500 million of these people are obese.
Leptin hormone and its relevance to obesity
In research conducted with obese people, the leptin hormone was present in the plasma serum in a highly concentrated form. It was seen that the leptin levels in the blood of people with a Body mass index of more than 25 were higher than then the people with less than 25 Body mass index.
There is a direct proportion of body fat ratio and leptin concentration.
Leptin hormone
The leptin hormone, which is mostly secreted by the fat cells, gets its name from Greek word leptos which means thin. Its common name is satiety hormone. The discovery of this hormone was in 90's years. The leptin gene is located on the 7th chromosome and it is a protein structure consisting of 167 amino acids.
Leptin is a member of cytokine family.It is secreted from fat tissue and it can be found in 2 forms in the body. These are; leptin that is freely present in blood and leptin that is present as attached to a receptor.
But, why is leptin that important?
Leptin, alongside with insulin and with ghrelin which works exactly as opposite to itself plays an important role in forming and preserving the energy balance of the body. Just as how ghrelin increases our appetite, leptin creates the satiety signal. Of course in normal and healthy conditions.
About the energy balance of our body; when the energy received(food) is not equal to the consumed energy(motion, metabolism activities, exercise, etc.) obesity or weakness occurs.
Leptin functions
Leptin is a very important hormone in the regulation of body mass and food consumption. Also, leptin plays a role in many physiological events like regulation of metabolism, sexual improvement, reproduction.
Blood concentration of leptin is directly proportional to the amount of fat in the body. Because women have a higher fat ratio, their leptin blood level is higher. At the same time, testosterone is known to hold down the leptin level.
The half-life of leptin in humans is around 25 minutes. Leptin plasma concentration is not constant and it has a circadian variation. The levels will start to rise in the afternoon, reach its peak value after midnight and towards sunrise, it will reach its lowest levels. Especially, between 11 a.m and 5 p.m, leptin levels are the lowest. And leptin levels are at max while sleeping.
The increase of leptin levels in plasma creates satiety feeling by passing the blood-brain barrier and activating the receptors in the hypothalamus.
Obesity is caused by lack of leptin value and leptin resistance.
Leptin resistance syndrome
For leptin to be active it needs to pass the blood-brain barrier and connect to the receptor. The defect of the receptors causes leptin resistance.
Leptin amount will not be considered enough, more leptin will be needed and for this more, fat tissues will be needed. So, the perceived leptin level will need to get higher and higher every time. And
because of this resistance, the body will need more resources to secret more leptin, and of course, this resource is the fat tissue. The outcome of this cycle will be increased fat tissue and obesity.
As a result of leptin resistance, we will start to eat more, because our brain will tell us to eat in order not to die. And we store more fat. Of course, more leptin will be secreted but the defect in the receptor will not be able to sense this and the stored fat tissues will cause obesity.
Diet exercise and losing weight
Actually, when we look at the longtime diet results, we can't say that anyone is losing weight. Because the decrease of fat tissue as we lose weight also decreases the leptin amount as well and the satiety feeling will inherently go away too. Leptin resistance will not work backward. For example, if you are secreting less amount of leptin, your brain won't consider it as enough. And as a natural result of this, you will gain the weight as fast as you lost it. Because your body needs leptin.
Because of this, the best weight loss program will be getting especially your endocrine secretions checked and receiving guidance from a doctor.
The right eating and exercise habit:
There should at least be 4 to 6 hours in between each meal (so leptin could be sentenced), breakfast with proteins in mornings (to keep you full at the hours when leptin hormone is secreted the least), long time and moderate intensity exercises. It is known that short and intense exercises decrease the leptin levels.
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images sources: 1 2 3 4 5 6 7 8 9
references:
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2829242/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2430504/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2967652/
- http://joe.endocrinology-journals.org/content/223/1/T71.full
- http://www.who.int/mediacentre/factsheets/fs311/en/
- https://www.nature.com/articles/0802142
Leptin, in the hypothalamus, inhibits the feeding center in the brain and as a result appetite is reduced or lost, so that's when we stop eating?
Basically, no matter the amount of leptin in circulation, in Leptin Resistance Syndrome, we continue to eat? Wow!
Leptin is secreted when plasma insulin level increases. if the receptor functions are not working we continue eating.
Yes, I was educated by your piece.
My understanding is that true leptin resistance syndrome is incredibly rare?
I believe leptin resistance can be a result of obesity as well, as a large amount of adipose tissue affects the regulation of leptin. This is what I found doing a quick search:
From a review by Klok et al.. They give some studies as evidence, but don't have the time to look through them. If you're not familiar with the term BBB, this is the blood-brain-barrier.
Relationship between obesity and leptin resistance, it s look like a closed chain ring. affect each other . Thanks a lot for your valuable contribution.
Thanks for the link... yeah I was only aware of the genetic condition that affects the leptin receptor directly. I wasn't aware that the sensitivity of the whole feed-back loop can be compromised due to obesity. Sounds a bit like the duel problem of insulin resistance and feedback control in diabetes!
Oh wow, good post - would the lack of leptin correspond to the 'empty feeling' in my stomach, telling me that I should eat something? From my experience, that's certainly a hard feeling for me to ignore...
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