Does Leptin Make You Fat?

Well, in a word, yes.

Leptin is a hormone produced by the fat cells in the body.  When the fat cells are full of stored fat, they produce leptin.  This is sensed by the brain and decreases appetite, while increasing calorie expenditures (less calories in, more out).  It is part of the body’s complex system designed to regulate energy storage.

If, for instance, a human goes through a drought where there isn’t enough food, at first the cells release stored fat to be used for energy.  As the drought goes on, leptin levels go way down.  This first of all makes the person hungry, and also decreases calorie expenditure so the stored fat is used sparingly.  When the drought is over and food is plentiful again, the person eats until the fat stores are replaced, when leptin levels rise again and appetite decreases and the metabolism goes back up.

OK, so now we know that high leptin levels make you feel full.  What happens in an obese person?  Interestingly, tests have shown that leptin levels tend to be HIGH in obese people, especially those who have diabetes.  Why is this?

Last week we talked a bit about fructose and how it contributes to weight gain.  Remember, fructose (present in ALL sweet foods) makes insulin resistance worse, and also contributes to LEPTIN resistance.  Just like insulin resistance, where the pancreas makes insulin but the body tissues don’t respond to it normally, there is also LEPTIN resistance.  The fat cells make leptin like crazy, trying to signal that there is plenty of energy storage and there’s no need to take in more calories.  But the brain doesn’t get the signal.

So how can we increase leptin levels and decrease leptin resistance?  The most important leptin sensitizer is actually getting enough sleep!  Sleep deprivation (less than 6 hours per night) lowered leptin levels and has long been known to cause weight gain.  If you are obese the simplest intervention you should make is to sleep at least 7-8 hours every night.  If you wake up tired after 8 hours of sleep, make sure to have your doctor check for sleep apnea.

Interestingly enough, bariatric surgery dramatically corrects the leptin resistance and lowers leptin levels as it promotes weight loss.  This is definitely NOT completely understood but it is becoming clearer all the time that the main mechanism of bariatric surgery-related weight loss is not mechanical at all but hormonal.  Bariatric surgery alters the hormones related to hunger and satiety, which also regulate fat storage and mobilization.

There are a few supplements that help increase leptin levels.  One is omega-3 fatty acids, usually taken as fish oil supplements.  Another is melatonin.  Two others are L-carnitine and conjugated linoleic acid (CLA).  Remember, megadoses of these supplements should NOT be taken with an eye to promoting weight loss.  All supplements have risks and should be used under the direction of your doctor.

Weight loss is complicated!  More and more research is coming out showing that the cause of obesity is NOT simply eating too much and not moving enough.  In addition to watching your calorie intake and getting active, if you’re trying to lose weight you should definitely avoid sweet foods and beverages wherever possible and make sure to get enough sleep.  This will help keep your leptin from working against you!