Leptin is a hormone, an active body chemical, produced by all are white adipose cells; our fat. For what seems like forever, we were taught that our adipose tissue, our fat, did nothing except store engird and keep us insulated. As it turns out, the scientists got this one way wrong. So, fat produces many hormones that effect our energy balance, most potent is leptin. So lets break it down.
[For more on the function of adipose tissue please see the post on “Fat just isn’t what we thought it was“]
Where does it come from?
Leptin is made in the Adipocyte, what you might call a fat cell. we have two 3 types of metabolically active adipocytes. We call them White adipose tissue, the fat around our bodies, on our arms, legs, etc; Brown Adipose Tissue, found in very small amounts though out the inside of our rib cage; Visceral Adipose Tissue, found in our bellies surrounding all our organs (this is the bad stuff).
White adipose tissue and Visceral adipose tissue produce leptin.
When is it produced?
Leptin is produced by our adipocytes. The amount fluctuates a little through out the day. When leptin levels are at their highest, you feel satiated, full, not hungry; your not searching for food. You may even feel a little happier or like socializing more. 
What does it do?
Leptin’s main job, as we can tell, is the maintenance of long term energy. It has receptors in the brain that work on the “Weight loss Pathway”. Higher leptin levels stimulate “thermogenesis” or better said, it increases expenditure of energy a.k.a. weight loss. It works to tell the brain that we have enough energy stored, so no more need to put more in. The amount of leptin we have circulating in our blood is directly dependent on our adiposity, our fat mass. As we gain weight levels increase, and those levels go down with weight loss.
Leptin don’t only work in the brain, we are discovering new receptors through out the body. It has effect on:
- thyroid hormone
- regulation of how our immune system functions
- development of new red blood cells
- development of blood vessels
- and bone development
What happens with weight loss?
When you begin to lose weight You leptin levels will fall dramatically. On the graph above, the Green Arrow indicates the Lowest level of leptin but there has only been 1/3 of the total weight loss! So that means the amount of leptin lost is huge compared to the little amount of weight loss. This big drop in leptin, results in never feeling satiated or full. It is why Will Power never seems to be enough. This large drop in Leptin, with the large increase in Ghrelin with weight loss, are your body’s attempt to prevent you from starving. But, we aren’t starving, we are at risk for diabetes, high blood pressure heart attack and stroke; our brain does not realize that. This is a big reason why diets fail, or we regain the weight we lost, and even a little more. Our bodies want to get back to the same leptin level that were we previously at, so we gain more weight and feel that our body has sabotaged our weight loss plans.
Weight loss is not a one time battle. It is a war, that will continue though out our lifetime.
Can I make it stop?
Unfortunately not yet. Doctors and scientists have tried developing Leptin as drug that can be injected. It kept the leptin levels elevated, but it resulted in significant skin irritation. Also, as the drug was administered , higher and higher doses were needed to maintain the effect. So while not a complete failure it never became available as a therapy.
There is also a syndrome of Leptin Deficiency. Individuals with leptin deficiency will never produce enough leptin to feel full. This is a very rare disease, but what is much more common is Leptin Resistance. There is no one cause for leptin resistance and we are starting to understand more and more. But for now think of it as the brain needing a higher level in the blood as time goes by because the restores just don’t recognize it the way they used to. And the only way to get more Leptin is more adipose. We eat more, because we fell less full; then store more energy for the famine that likely will never come.
How can I still Lose weight?
Thousands of people have lost and continue to lose weight, and keep the weight off, despite the decrease in Leptin. The body does not work with just one hormone. There are many hormones that regulate our drive to eat, and to lose weight. They are controlled by time, stress, the sun, emotions and more. There are now a few medications available that help block the hunger pathway, or stimulate the “full” pathway that may help with weight loss. see: Weight Loss Drug Overview. There are also surgeries that may help you achieve your goals as weYou can be extremely successful with a plan that includes lifestyle modification, psychosocial support, increased activity, and ongoing treatment with a physician trained in Obesity Medicine.
