Leptin is a fascinating hormone. Until 1994, we did not even know if its existence. And yet all along, leptin had been there quietly in the background. It's starting to look as if leptin is the master switch for appetite, blood sugar, fat-burning, bone health, and fertility.
Leptin is a key message from the fat to the brain. It's supposed to say:
"We have enough fat stores. You don't need to eat more. You should burn off some of this fat." And, finally: "We have enough food to make a baby."
But what happens if that message goes astray? What happens when the brain stops listening to the leptin coming at it? The message doesn't get through, and the result is:
- constant hunger
- inability to lose fat stores
- insulin resistance
- elevated blood sugar
- increased perspiration
- reproductive problems such as PCOS
Consumption of refined carbohydrates, especially sugar and fructose causes an excessive release of leptin. Over time, when the brain is exposed to this much leptin, it has to stop listening. It has to adjust, because from the brain's perspective:
"Surely that cannot be the correct information? We cannot have eaten that much sugar! There must be some mistake. I better change the way I do things."
The entire leptin signalling system is thrown off the rails. Leptin is no longer the helpful satiety message that it once was. It has a dark side.
When the brain becomes leptin resistant, it does not know that there are enough food and enough fat stores. It is under the false impression that food is scarce. It sends out powerful messages to eat, and it tells the body to store fat.
The leptin resistant person wants to eat all the time. Fat tissue accumulates and secretes more and more leptin, but the brain still isn't listening. It still thinks the body needs more food! In the meantime, the excess leptin does damage. It signals the liver to secrete excess blood sugar, it increases inflammation in the body, and it interferes with normal ovulation and reproduction.
Master controller of blood sugar. Potential cure for diabetes?
In a recent ground-breaking study on mice, leptin supplementation was shown to completely normalise blood sugar, irrespective of insulin. Leptin does this because it prevents the production of glucose by the liver. Experts are stunned by the development. It means a complete rethink about blood sugar, and it could pave the way to a cure for diabetes.
Why rapid weight loss can never "hold"
Lean people have a low leptin set-point. In other words, their brains are accustomed to low leptin. If leptin drops a little more from hunger, then the brain response is a reasonable fashion. It signals the body to eat, but it doesn't trigger a massive fat storage reflex. This is normal leptin sensitivity.
Overweight people, on the other hand, generally have a high leptin set-point. They are used to a lot of leptin, so when leptin drops due to calorie restriction and fat loss, the brain panics. It sends out strong hunger messages and signals the body to store fat. That post-weightloss drop in leptin may continue for up to 1 year. In other words, the hormonal message from the body after weight loss is to eat more and to regain the weight.
Rapid weight regain can be prevented by not allowing leptin to drop too low during the weight loss phase. A large meal once per week (but not refined sugar) will cause a beneficial leptin surge to stimulate metabolic rate, and suppress appetite. This can be part of a successful strategy to reduce the leptin set point slowly over time.
Strategies to reset your leptin signalling:
- STOP eating refined sugar. All of it. Sugar seriously disrupts leptin signalling. It causes constant hunger and makes it impossible for the body to let go of fat.
- Get 8 hours sleep. Sleep improves leptin sensitivity.
- Avoid antibiotics. Antibiotics disrupt leptin balance and can cause weight gain.
- Do not crash diet. Losing weight too quickly will cause rapid leptin drop and suppress metabolic rate for up to 1 year.
- Do not snack between meals.
- Enjoy the occasional big meal to trigger leptin surge and increase metabolic rate.
- The natural supplement resveratrol has been shown to inhibit leptin secretion from fat cells.
- Zinc has been shown to regulate leptin levels.
- Avoid, when possible, prescription medications that interfere with leptin such as certain blood pressure medications, steroids, and others.
Blood test for leptin
A simple blood test for leptin is available from Sensible-Alternative naturopaths.
1) Lee, Y et al. Glucagon Receptor Knockout Prevents Insulin-Deficient Type 1 Diabetes in Mice. Diabetes, 2011; 60 (2): 391 DOI: 10.2337/db10-0426
2) Sumithran P et al. Long-term persistence of hormonal adaptations to weight loss. N Engl J Med. 2011. 365(17):1597-604.
3) Szkudelska, K et al. The inhibitory effect of resveratrol on leptin secretion from rat adipocytes. Eur J Clin Investigation. 2009; 39(10):899-905.
4) Mantzoros CS. Zinc may regulate serum leptin concentrations in humans. J Am Coll Nutr. 1998. 17(3):270-5. PMID: 9627914