The Weekly Vlog

The Law of Leptin

Feb 04, 2015

I’ll never forget the day I first heard about Prader-Willi Syndrome.

I was in the Neonatal Intensive Care Unit (NICU) at Strong Memorial Hospital in Rochester, New York. My twin babies Alexis and Zoe had just been born prematurely, each weighing less than one pound, seven ounces. There was a 4% chance that they would both survive and grow up without any disabilities. David and I were essentially living in the NICU, staring through the fiberglass of the Isolettes at our tiny, ET-like daughters, whispering prayers through the peep-holes.

In those infinite hours that now seem like they existed in a different Universe, we became very close with the parents of the other premature babies in the same small pod as Alexis and Zoe. The D2 pod.

One day, one of the D2 moms came back from a meeting with the Attending Physician looking hollow and tortured. She and I linked arms and walked over to the private pumping room to pump some breast milk, more out of habit than necessity—neither my twins nor her daughter could tolerate actual breast milk. It all got frozen for some sunny future time when we might get to bottle feed it to our hopefully-then-healthy babies.

I asked her what the doctor had said.

She said he’d told her that her daughter may have Prader-Willi Syndrome.

What’s that? I asked.

She described a rare condition marked by cognitive deficits, short stature, behavioral challenges, and a driving, all-consuming motivation to eat, leading to extreme morbid obesity and early death.

They say I’ll have to padlock my refrigerator door, she added.

I let it sink in.

I gave her a hug.

Then it dawned on me that her baby was currently struggling to eat anything at all…that was the biggest challenge she was having.

Yeah, she said. It starts out that way. Then in a few years the nonstop eating will kick in.

My own eating was under control by then, and had been for several years, but it did dawn on me that I could relate to her poor baby girl. Once upon a time, my refrigerator wasn’t safe in my presence, either.

My musings, it turns out, may not have been so very far off the mark.  A recent New York Times Magazine article on Prader-Willi Syndrome paints the picture of a continuum, with insatiable Prader-Willi eating on one end, regular each-bite-brings-you-closer-to-full eating on the other end, and the eating of most overweight and obese folks somewhere in-between, but maybe a bit closer to the Prader-Willi end.

It turns out that Prader-Willi Syndrome is caused by congenital abnormalities on chromosome 15 that lead, in some yet-to-be-discovered way, to the brain not being able to process leptin.


Once again, it all boils down to leptin.

Leptin is the “I’m not hungry and I feel like being active” hormone.

If we all had plenty of leptin circulating in our blood, and our brains could actually register it properly, everyone would be slender, energetic, and upbeat.

With leptin on board, we naturally stop eating because we feel full. Our metabolisms rev, and not only does this make us thin, it literally leads to a feeling of happiness.

In short, leptin makes us happy, thin, and free.

But without leptin on board, we become the human equivalents of the mice that first led scientists to discover leptin, just over 20 years ago.

"Positional cloning of the mouse obese gene and its human homologue"
Zhang Y, Proenca R, Maffei M, Barone M, Leopold L, Friedman J (December 1994)
Nature372 (6505): 425–32. DOI:10.1038/372425a0. PMID 7984236

Those mice were missing the gene that makes leptin, and therefore they had none at all.

They practically never moved.


They just sat by the food trough and ate all day long.

And even though all they had to eat was generic rat pellets, they grew to be very, very fat.

The only way to get those mice to move was to switch the location of the food trough. Then they would waddle, slowly, over to the new location, and plop down and eat.

You could come back a week later and they’d still be there.


Were those mice morally defective?



Nah. They just needed some leptin.

And sure enough, given a few leptin injections, those mice lost interest in food, started voluntarily climbing into the hamster wheel, and got skinny again.


You know, I really wish I could have been a fly on the wall when the news of leptin first made its way into the boardrooms of the big pharmaceutical companies. I can just imagine the melee.

After all, hormones are easy to put into pills.

(Just think, “the pill.”)

And, just like with the pill, leptin could theoretically be manufactured in nearly endless synthetic configurations.

Each totally patentable.

And each worth billions. Maybe trillions.

But as fate, or biology, would have it, the celebrations were premature.

“Leptin resistance - or why leptin fails to work in obesity."; El-HaschimiK., Lehnert H.
Experimental and Clinical Endocrinology & Diabetes 2003 Feb; 111(1): 2-7. DOI: 10.1055/s-2003-37492.

We all found out pretty quickly that leptin, in pill form, doesn’t make an overweight person lose weight.

Direct leptin injections don’t even make an overweight person lose weight.

Why not?

Well, generally speaking, people are not overweight because they are missing the gene that makes leptin. We don’t have the same problem that those mice did. They had no leptin at all. We do.

In fact, it turns out that overweight people have lots of leptin circulating in their blood. Even more leptin, ironically, than skinny people.

"Serum immunoreactive-leptin concentrations in normal-weight and obese humans"
Considine R, Sinha M, Heiman M, Kriauciunas A, Stephens T, Nyce M et al. (1996)
N. Engl. J. Med. 334 (5): 292—5. DOI:10.1056/NEJM199602013340503, PMID 8532024

This stands to reason, actually, because leptin is produced by fat cells.

Leptin is the feedback mechanism that evolved to keep the weight of a human being in equilibrium.

After an especially abundant harvest and several days of unrestrained eating (leading to a bit of weight gain), leptin is the signal that would kick in and say, “You don’t need to eat anymore right now. Ugh! That’s enough food! But wow, I feel great! Maybe I’ll go build a hut! Or find a mate! Or kill a wildebeest!”

So why isn’t the leptin feedback mechanism working today? What’s causing the malfunction of this finely-tuned system?

The general answer to this question has been known for many years, but the deeper, underlying cause was only discovered very recently.

The general answer is that people today are becoming leptin resistant. Their brains are not registering or “seeing” the leptin that’s circulating in their blood.

"Advances in understanding the interrelations between leptin resistance and obesity"
Haitao Pan, Jiao Guo, and Zhengquan Su
Physiology & Behavior (130)2014). 157–169. DOI:10.1016/j.physbeh.2014.04.003, ISSN 1873-507X, PMID 24726399

And hence, they sit on the couch every night and eat.

But what’s the underlying cause of leptin resistance?

This, my friends, is the holy grail of obesity research.

Solve the puzzle of leptin resistance, and you’ve cracked the code of the obesity pandemic.

And just recently, it happened.

Researchers at UCSF medical center discovered what’s causing widespread leptin resistance.

The cause is INSULIN.

Yup, insulin.

Insulin is blocking leptin in the brain.

"Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease"; Lustig, Robert H.
Plume: New York, 2012, page 47.

Where does this happen?

Well, it used to be thought that it happened in the hypothalamus, which governs most eating behavior. But more recent research shows that the blockage may be even deeper, down in the brain stem.

So rising insulin levels are a key cause of the obesity pandemic we're now faced with. And it's affecting us very early in life. Research on overweight kids has shown that their average insulin levels rise 45% from grade school to high school. They're being set up for a lifetime of obesity by the rewiring of their brains that happens with every bite they take.

And note that we’re talking about “average” insulin levels. We’re not talking about the insulin spike cause by eating some one-off snack out of a vending machine.

So what’s the treatment? What can we do?

Clearly, we have to lower insulin levels. And not right-after-eating insulin levels, but 24/7/365 insulin levels.

But why have our insulin levels gotten so high in the first place?

I have two words for you.

You guessed them.


The average American is consuming 152 pounds of sugar and 146 pounds of flour each year. That’s nearly ONE POUND of sugar and flour per-person EACH DAY.

(And some of us don’t eat any sugar and flour, so some folks are eating way more than that, to round out the average.)

Sugar and flour aren’t foods, my friends. They are toxic drugs.


That’s not an opinion, that’s a scientific fact.

The technical description for sugar is a “chronic, dose-dependent, hepatotoxin.”

That’s “toxin” as in “poison.”

Sugar is a “hepatotoxin” because it’s made up of fructose, which, in high quantities, specifically damages the liver.

Flour is a “chronic, dose-dependent toxin” because its toxic affects aren’t limited to the liver. Flour is made up of glucose, which is processed everywhere, so at high levels, flour damages every cell in the body.

Wheat flour concentrates the complex carbohydrate amylopectin-A which is digested to produce glucose. It spikes blood sugar more than other starches. Willam Davis, Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back to Health (New York: Rodale, 2011), p. 33.

What can we do when the foods we’re eating are poisoning us?

And what about our kids?

What can we do when the foods our kids are eating, in school, at camp, in restaurants, and at home, are threatening their lives?

That’s exactly the question that every parent of a child with Prader-Willi Syndrome has to face.

So, not surprisingly, we can learn a lot from the treatment of Prader-Willi Syndrome.

There aren’t a lot of inpatient treatment centers for Prader-Willi, but one of the best is the Center for Prader-Willi Syndrome at the Children’s Institute of Pittsburgh.

How do they handle food at the Center for Prader-Willi Syndrome when their patients have been known to lie, steal, and even break into neighbor’s houses to get food? Some patients are so obsessed with eating that if they get their hands on an unlimited supply of food they might literally eat until their stomach linings rupture and they die.

Not surprisingly, the inpatient clinic has developed some pretty great strategies for feeding their patients.

And they work.

Funny enough, their approach dovetails nicely with Bright Line Eating™, especially the Bright Lines of MEALS and QUANTITIES.

At the Center for Prader-Willi Syndrome, nobody eats anything outside of meal time. All food cues have been removed. In fact, food is not even on the floor that houses the patients. Food arrives on trays right at meal time, and then everything is taken away. Quantities are weighed and measured.

Do the patients lose weight? Of course they do.

But what happens to them psychologically when they are cut off from access to the food they crave so much?

Can they withstand the torture?

Well, just like anyone who does Bright Line Eating™ will tell you, it’s hard for them at first, but it doesn’t stay that hard forever.

In fact, after a brief adjustment period, they’re not tortured at all.

They’re happy.

And what about the rest of us?

It turned out that my friend’s daughter didn’t have Prader-Willi Syndrome after all. And Alexis and Zoe hit the 4% miracle jackpot and are growing up happy and healthy.

All three of them dodged those early bullets. But they have now been released into the general population, where insulin levels are rising, poisons are peddled as treats, and moms and dads are left to scramble and do their best to figure out how to serve their kids real food.

Is my friend’s daughter better off? Without question. But I have to say that my heart warms when I think of the patients at the Center for Prader-Willi Syndrome at the Children’s Institute of Pittsburgh. The Bright Lines around food that the Center diligently maintains are keeping them happy and safe. If you ask them, they’ll tell you that they are getting to live in the only environment they have ever known where they can finally stop thinking about food and start living life.

With love,


P.S. -- As always, I look forward to reading your comments. Scroll down and share your thoughts!

Click here to listen to this episode on Bright Line Living™ - The Official Bright Line Eating Podcast.

Susan Peirce Thompson, Ph.D. is a New York Times bestselling author and an expert in the psychology and neuroscience of eating.  Susan is the Founder and CEO of Bright Line Eating®, a scientifically grounded program that teaches you a simple process for getting your brain on board so you can finally find freedom from food.

Learn More

Register today for the free Bright Line Eating Masterclass!