Let’s talk about Leptin and energy metabolism

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Leptin is a hormone that has come to my attention because it has such an important and powerful role in the body, particularly in energy metabolism.


This hormone is produced in the white fat cells and during the day sends messages or information to the brain;, specifically the hypothalamus.  These messages tell the brain what the energy status of the body is, meaning you can stop eating now as you have enough energy.   The hypothalamus then uses that information and sends it’s own messages,  based on the information from the Leptin.   This may include messages to the thyroid, pancreas, adrenals, and the sex glands, on how to function or perform.


When this process is in balance and Leptin is able to communicate to the hypothalamus, then the system works well. Our hormones are balanced, we can eat and feel satisfied, we stay at a stable weight, we sleep well, our metabolic rate is normal, we are insulin sensitive and we are fertile (for those of child bearing age).


Problems arise when that Leptin message can not get through to the brain.  In this situation your hypothalamus has no idea how much energy you have, so it literally thinks you are starving ,no matter how much or little you are eating.    The hypothalamus sends a signal is sent to your thyroid to slow your metabolic rate and start to conserve energy, another signal is send to the stomach to produce the hunger hormone, Ghrelin.  In this situation it is very hard to use fat as your primary energy source.  In other words it is very hard to lose fat and you may start to gain weight and have no idea why.  You are eating all the right things and exercising as you have been told too.


You are hungry even when you have just eaten a great meal.  You find yourself standing at the fridge or pantry looking for something, even though you don’t physically feel hungry.  You eat after dinner and maybe even wake in the night and eat.  You have uncontrollable cravings or spend a lot of energy and will power trying not to snack. We constantly tell ourselves, “we will start our diet tomorrow”, but never can.  No amount of will power can compete with this survival mechanism.


You have become Leptin Resistant!


So what makes us Leptin resistant?

Leptin Resistance - energy metabolism


There are a number of reasons why we can become Leptin resistant but the big reasons include;  chronic inflammation and stress, too many carbohydrates in the diet, eating too often; and not getting enough sunlight, particularly in the morning.  We are basically out of our natural rhythms and breaking the laws of nature.


Chronic Inflammation

Chronic Inflammation is a response by the body to protect itself from toxins such as excess fat cells, industrial vegetable and seed oils, sugar, refined carbohydrates, chemicals in our food and water, chemicals in our beauty products, pollution, mould etc.  It has a direct affect on the ability of Leptin to communicate with the hypothalamus and therefore the energy status, repair or fat burning functions.


Lack of natural sunlight and circadian clock dis-regulation

The hypothalamus has photo receptors that helps Leptin enter the gland, so it can give it’s instructions.  We need the morning sun in our eyes and on our skin, to set our natural circadian rhythms and also receive messages from the sun to set hormones, body clock, when to wake, when to eat, when to sleep, when to repair etc.


Insulin resistance

Having high insulin can block the Leptin receptors at the hypothalamus and stop the Leptin message from getting through.  High insulin is related to, too many carbohydrates in the diet and eating too often.  However, Leptin resistance generally proceeds insulin resistance by about 5 years.  Note: Once you have Leptin and insulin resistance, adrenal resistance is not far behind, in relation to stress and high cortisol.  The three go together.



Snacking disrupts your circadian clock.  From an evolution point of view, we never evolved to eat all the time.  We never have a winter, where food is scarce.  Eating all the time increases our insulin levels and can lead to insulin resistance, which in turn impacts the signalling of Leptin to the hypothalamus.


Timing of meals is very important.  Eating and digestion fit within a rhythm or pattern.  We eat, 30 minutes later our insulin spikes. It then takes our body 2 to 3 hours for our insulin to go back to baseline.  The body needs a further 2 to 3 hours to perform other functions before we eat again.  You have to remember that the hormone, insulin, is also our fat storing hormone so if you eat too often your insulin levels never gets back down to baseline. You can never burn fat as fuel because your body needs to burn all the sugar or carbohydrates you are consuming before it can burn fat.


Eating close to bedtime

At around midnight Leptin, along with Melatonin, peak and perform another important job when we sleep.  At this peak, Leptin enters the hypothalamus and sets a chain of instructions to start repairing your brain and body, a process called autophagy.  At this time your body starts to burn body fat as fuel also.  However, if the message from Letpin cannot get into the hypothalamus both these processes cannot occur.  Eating too close to bed can have a big negative impact on this process.  As we spoke about in snacking, after we eat we get an insulin spike and if this insulin spike is happening at bedtime, it impacts Leptin’s ability to enter the hypothalamus and therefore perform it’s repair and fat burning tasks.



Richards, 2009, Mastering Leptin, Third Edition, Wellness Resources, USA
Kruse, 2013, EPI – PALEO – RX, First Edition, Optimized Life PLC, USA
Khodamoradi, The role of leptin and obesity on male infertility, May 2020, PMID: 32205811
Figueiro, Light modulates leptin and ghrelin in sleep-restricted adults, Aug 2012, PMID: 22988459
Skinner, Chronic Light Cycle Disruption Alters Central Insulin and Leptin Signaling as well as Metabolic Markers in Male Mice, Oct 2019 PMID: 31276158
Clawson, Continuous access to snacks from weaning onwards in female rats causes weight gain, insulin insensitivity, and sustained leptin resistance in adulthood, Mar 2019 PMID: 30472395


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