Leptin, a recently discovered hormone, regulates body weight by suppressing food intake and/or increasing energy expenditure.
Leptin is a very powerful and influential hormone produced by fat cells. Science has discovered that leptin is the most powerful metabolic regulator that tells your brain whether you should be hungry, eat and make more fat.
Basically, leptin is the way that your fat stores speak to your brain to let your brain know how much energy is available and, very importantly, what to do with it.
Ordinarily as you gain weight, the body should secrete more leptin from your fat cells. This in turn tells your brain you have enough stored and therefore reduces appetite.
But there is a problem!
Unfortunately many people have something called "leptin resistance". This means that no matter how much leptin you create from your fat cells, the brain doesn't see it. This leads to a cascade of your brain thinking you are starving ======> you burn less calories ====>your appetite goes into overdrive and finally every bit of food you eat gets stored on your belly!
Until you address leptin resistance, you're not going to lose weight!
Optimal Leptin Levels
Your goal is to keep your leptins below 12, however, not too low. Researchers have discovered that leptins too far to the low side has been associated with dementia or Alzheimer's.
A leptin above 12 is not considered healthy.
Leptin levels can now be measured with a simple blood test. Levels above 12 are linked to weight gain, accelerated aging, increased risk of infertility, diabetes and heart attack. In addition, high leptin levels are associated with belly fat and numerous cancers
Leptin rises if you don't sleep well, and if you have any kind of perceived stress.
If you are having difficulty losing weight, we recommend you get your leptin checked. Remember you want it under 12. From a thyroid perspective, if your leptin is above 12 you will commonly see low T3 (the most metabolically active thyroid hormone) and elevated reverse T3. This is not good for those trying to lose weight. The thyroid medication Synthroid (Levothyroxine) is aT4 medication and should be used with some level of caution when high leptin levels are seen. The take away from this thyroid connection is the fact that reverse T3 means T4 is not being effectively converted into the metabolic workhorse hormone, T3.
You become leptin resistant by eating the typical American diet full of sugar, refined grains, and processed foods. The solution is to eat a diet that emphasizes good fats and avoids blood sugar spikes. Basically a diet that emphasize healthy fats, lean meats and vegetables, and restricts sugar and grains.
For a full thyroid/leptin work-up, I recommend a practitioner knowledgeable in functional medicine.
- Kozlowska, Rosolowska-Huszcz. Leptin, thyrotropin, and thyroid hormones in obese/overweight women before and after two levels of energy deficit.Endocrine. 2004 Jul;24(2):147-53.
- Hsieh CJ1, Wang PW, Wang ST, Liu RT, Tung SC, Chien WY, Lu YC, Chen JF, Chen CH, Kuo MC.Serum leptin concentrations of patients with sequential thyroid function changes. Clin Endocrinol (Oxf). 2002 Jul;57(1):29-34
Ríos, Cisternas, Arrese, Barja. Is Alzheimer's disease related to metabolic syndrome? A Wnt signaling conundrum.Prog Neurobiol. 2014 Jul