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The Definitive Guide to Leptin and Weight Loss

The Definitive Guide to Leptin and Weight Loss

If you want to learn the truth about leptin’s role in weight loss, and how to make sure it works for and not against you, you want to read this article.


The mainstream obesity witch hunt has already sentenced insulin to death, and now has another devil-worshipping hormone to railroad: leptin.

Often called the “obesity hormone,” leptin imbalances and dysfunctions are now being targeted as one of the leading drivers of fat gain in humans, which has, of course, given rise to all kinds of diets and supplements that claim to neutralize this hormone’s evil, fattening ways.

The first thing you need to realize about claims like these is this:

Weight loss advice that strays from or ignores completely the foundation of energy balance is almost always, as Shakespeare said, falser than vows made in wine. 

You’re not going to eliminate the doughy evidence of years of overeating and under-moving by balancing a hormone or adding or removing certain foods from your diet.

Healthy weight loss isn’t complicated, but it requires self-discipline and effort; you’re going to have to regulate food intake and exercise for weeks or months, depending on how much fat you want to lose.

That said, like insulin, while leptin doesn’t have the power to “allow” or “disallow” weight loss, it can work for or against your efforts to get leaner, making the process easier or tougher.

Let’s find out why.

What is Leptin?

Leptin is a hormone produced by fat cells that has many functions in the body: regulating hunger, your metabolic rate, appetitemotivation, immunity, fertility, and libido, to name a few. Its main role, however, relates to the regulation of body weight.

In simple terms, leptin tells your brain that you have enough energy stored in your fat cells and that your body can expend energy at normal rates, including metabolically “expensive” functions like muscle growth or pregnancy, eat normal amounts of food, and engage in normal levels of physical activity.

If you restrict your calories to lose fat, leptin production decreases, which tells your body that it’s in an energy deficient state and that it needs to expend less and consume more. It accomplishes this through several mechanisms: reduction of basal metabolic rate and non-exercise activity, and stimulation of hunger, to name a few.

Here’s how the process works in a nutshell:


In healthy humans, this “feedback” loop works incredibly well and helps us maintain normal levels of body fat.

We get hungry, we eat until our body tells us its full, it stores some of the food as fat, we go about our day, expending energy and burning fat, our body tells us it needs more energy, we eat until full, and the cycle repeats.

As you can see, leptin itself is hardly an enemy–its goal is to prevent you from getting fatter and fatter over time. That said, we can turn leptin against us through poor eating and exercise habits…

Too Much of a Good Thing: Leptin Resistance

Obese people have high amounts of body fat, but guess what else they have an abundance of? That’s right–leptin.

The more energy stored in your fat cells (the fatter you are), the more leptin your body produces

Why, then, are obese people often driven to eat so much? Why aren’t their brains sensing all the leptin in their blood and realizing that, holy shit, we don’t need food for a long damn time, and completely turning off hunger and the desire to eat?

The answer lies in what’s known as leptin resistance.

Like insulin resistance, leptin resistance is a condition wherein the body becomes less sensitive to leptin’s signals, which then plays havoc with the appetite and metabolism.

There are different theories as to how this works exactly, but the bottom line is this: leptin levels can be abnormally high but the brain thinks the body is in an energy-starved state and thus takes the actions mentioned earlier to increase energy intake and reduce output.

This “short circuits” the normal weight-maintenance process diagrammed above, and causes a vicious cycle:

  1. Eat food
  2. Gain fat
  3. Produce leptin
  4. Feel hungry
  5. Eat more
  6. Produce leptin
  7. Feel hungry
  8. Eat more
  9. Ad nauseam

In this way, leptin resistance causes overweight and obese people to naturally tend toward eating too much and moving too little, which causes them to get fatter and fatter. And as you can see, the best way to avoid falling into this trap yourself is never becoming overweight in the first place.

Think of obesity as a pit of quicksand filled with doughnuts and cheeseburgers. The more you eat, the more you weigh, the more you sink, and the harder it is to get out.


This doesn’t mean that overweight people are doomed, though. Reducing fat mass reduces circulating leptin levels and also appears to “restore” leptin sensitivity. Yes, they may have to battle hunger a bit more than other people, at least in the beginning, but this too normalizes in time.

This also explains one of powerful the biological drivers of “yo-yo dieting” (rapidly losing and re-gaining weight): a person starves himself, crashing leptin levels, and then finally can’t take the hunger and misery anymore and is compelled to regain the lost fat to restore physiological “balance.”

How to Restore Leptin Sensitivity

If you want to never have to battle weight issues, you want to maintain high levels of leptin sensitivity. This way your brain can simply do all the work for you, regulating your appetite to ensure you remain at a healthy body fat percentage.

Health and fitness marketers have jumped all over this and produced a glut of special diets and supplements meant to balance and optimize leptin levels, but like most fad diets and “wonder supplements,” it’s a bunch of bullshit.

Here’s the “hard truth”…

If you want to restore leptin sensitivity, you can’t be overweight.

There’s just no way around this. If you’re overweight and don’t bring your total fat mass down to a healthy level, you’re never going to be able to eliminate your leptin resistance problems and you’re always going to struggle with preventing further weight gain.

And this means you’re going to have to maintain a calorie deficit by regulating food intake, which means you’re probably going to have to give up some of your unhealthier habits like eating too much junk food and drinking too many calories.

Don’t worry though–losing fat is quite easy when you know what you’re doing. You get to eat the foods you like, you don’t have to suffer through mind-bending hunger or cravings, and you don’t have to do hours and hours of grueling exercise.

If you want to maintain leptin sensitivity, you need to commit to healthy living.

No, I’m not talking about sacrificing your taste buds to the cult of “clean eating,” I’m talking about engaging in regular exercise and ensuring you don’t chronically overeat.

That’s not a lot for your body to ask of you. Don’t stuff it with food it doesn’t need and don’t condemn it to death by inactivity.

Like insulin sensitivity, leptin sensitivity is simply a byproduct of taking good care of your body, and if you focus on getting healthy, it takes care of itself.

How to Boost Leptin Levels to Help With Weight Loss

For most people, the first couple months of a healthy weight loss diet is smooth sailing. They exercise regularly and maintain a proper calorie deficit and their body fat percentage neatly declines week after week.

Eventually, though, progress slows. Energy in the gym wanes and workouts get harder and harder. The body composition goal, which seemed in the bag just a month ago, now appears further and further away.

For most people, this is where they lose heart and fall off the wagon and binge. And then binge again. And again.

But there’s hope. And it doesn’t involve dropping your calorie intake to dangerously low levels or frying your muscles with excessive cardio.

Instead, the “trick” is something you’ll relish: occasional overfeeding. Yes, that’s right–eating a bunch of food. Not just anything and everything, though–there’s more to it than that. This weight loss aid is known as “refeeding,” and it allows you to manipulate leptin levels to help keep your weight loss efforts on tack.

Check out this article on refeeding to learn more.

 What are your thoughts on leptin and weight loss? Have anything else to share? Let me know in the comments below!

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I'm Mike and I'm the creator of Muscle for Life and Legion Athletics, and I believe that EVERYONE can achieve the body of their dreams.

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Leave a Comment!
  • Ruud

    It’s funny, we had a lecture today at the university about the digestive
    system with ghrelin and leptin levels. I think it’s awesome that you write
    articles like these.

    Be conscious
    with everything that you do. Most of the time the simples things are the
    hardest to achieve.

    • Michael Matthews

      Thanks! I appreciate it.

  • Debbye S. Sparks

    Hey Mike, I’m doing my HIIT cardio before weight lifting. On a fasted state but taking BCAA’s.

    I’ve been taking my protein shake right after Im done with HIIT cause I immediately start lifting, so it’s like a “pre workout” shake, then I also have a post workout shake after Im done lifting. You think this is a good strategy?

    I’m just really trying to get rid of the stubborn fat -with fasted cardio- while also trying to make muscle gains. What ya think? I do like 25min on the stair machine, should I stick to 3x a week? Thanks!

    PS. Love whey+ and pulse! Pulse specially has helped me so much, thanks!

    • M

      Based on some of Mike’s articles and podcast episodes, I would suggest you split the weight and HIIT sessions, not follow one after the other… If this is not possible due to time constraints, lift before doing HIIT… You will feel fresher when lifting and will be able to lift heavier for sure…

      • Debbye S. Sparks

        Thank you “T” and “M”

        First, T, I’ve read all of his articles many times.

        M, yes, it is not possible for me to split my sessions. I remember Mike saying that about lifting first and cardio later, BUT that depends on the person, like for me, I like doing cardio first when I workout my upper body and cardio second when I workout legs.

        The only thing I’m worrying about is not breaking my fasted state by the time I do cardio, that’s why I like to do cardio second when I’m going to lift heavier -legs day- cause I don’t like lifting in fasted state, I still to weak for that.

        That’s why I asked if it was a good idea to take my protein shake after my cardio -to break the fasted state before lifting- and the other shake after my lifting to help with gains. It doesn’t matter which one I do first. Actually a recent study by ACE https://www.acefitness.org/acefit/expert-insight-article/47/5122/ace-research-study-sequencing-exercise-for/ suggest that doing cardio before lifting is the best choice, even though my thoughts are that it depends on your goals, your body composition and many other factors, as always.

        • Michael Matthews

          The reason why I don’t like cardio before lifting is HIIT is going to burn up energy that you won’t have for your lifts, whereas lifting first doesn’t really impair your HIIT in terms of effectiveness for fat loss.

    • T
    • Michael Matthews

      I would do the cardio after lifting, or better yet, separate altogether. If you’re going to do it after, I would BCAA, lift fasted, have a scoop of whey, and then do cardio.


      Thanks! Really glad to hear it!

      Could I ask a small favor? Would you mind writing a short blurb on the Legion products on my website, and copy and pasting those blurbs as Amazon reviews? It seriously helps with word of mouth, as you can imagine.

      If you’re cool with that, here are the product pages:







      Again, if you wouldn’t mind taking a few minutes to do that, I’d owe you big time! 🙂

      • Debbye S. Sparks

        But wouldn’t them I be missing the benefits of “fasted HIIT”?

        PS. Of course, I just wrote the reviews! I love pulse!!!!!

        • Michael Matthews

          Fasted lifting is plenty. If you reaaally wanted to, you could use BCAAs again instead of whey (before the cardio).

          Thanks! 🙂

  • LifeForMuscle

    Amazingly written article right there! *clap* *clap* *clap*

    WHEN ARE YOU GOING TO RELEASE “BLS 2” COME ON!!!!! (Sorry I just can’t wait) there are many things contradicting your articles. Like in BLS you said that you should not stay without protein for more than 4 hours and in the interment fasting article you said you can stay for more than 21 hours without protein.

    Sincerely , your biggest fan 🙂

    • M

      The book was launched a while ago… http://www.muscleforlife.com/bbls/

      I don’t want to be rude, but as his “biggest fan”, you should know that…

      • LifeForMuscle

        lol… that was harsh 🙂

        i know you released beyond bigger leaner stronger. but you always say that this book is for advanced lifter like 2+ years of lifting… i have been lifting for 4 months, so i dont find a reason to get this book.

        sincerely , your big fan 😉 (how about that? :D)

        • M

          Btw, I’m not Mike and I’m sorry, I didn’t mean to be rude… =)
          If you have been lifting for 4 months only, don’t worry about the next book, focus on what is in BLS and you will do just great… I wish I had found out about Mike’s work when I started as well instead of wasting time with stupid stuff from bodybuilding.com, so consider yourself very lucky…

          • LifeForMuscle

            haha , now i realized that you are not mike. got mixed up :D. im not used for other people than mike to reply to my comments so i automatically assumed that you were mike. well… this is awkward…

            thanks for the reply. dont be sorry 😉

            also your biggest fan 😉

    • Michael Matthews

      Whoa I missed this somehow. Thanks for the kudos! 🙂

      BLS 2.0 is coming out in January and as you’ll see, all confusions will be clarified!

      • LifeForMuscle

        thats soo close! CANT WAIT!

        • Michael Matthews

          Me too! 🙂

  • Jim anderson

    Hi Mike I’m 66 and been following you for a while,my question is about cardio,I have rotator cuff,and Achilles tendon problems,I’m thinking of using the rowing machine for cardio,is this a good idea?also I don’t lift heavy now I’m just into maintenance as I am quite happy with my phisique(well as happy as one can be),what do you think

    • Michael Matthews

      Yeah rowing is great cardio. That and biking are my fave.

  • Excellent article Mike!

    I was blown away to read about that guy who fasted for 382 day! =))) No way!

    Thanks for link!

    • Michael Matthews

      Thanks! I know! Crazy shit.

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  • estycki

    Appetite training swings both ways. Sometimes people say that if you undereat you get some kind of damage to your metabolism. I was extremely overweight, I have to admit you get to that point because you train your body to ignore the signals (like someone who ignores their body’s reaction to smoking or drugs etc). You just power through it, to a point where it’s easy to do and you don’t feel sick from it. I laughed at my skinny brother who would puke if his breakfast had more than two eggs. I would eat 5 eggs everyday since I was a teenager! How did I manage that when he couldn’t? I trained my body to accept it! Maybe this was inducing leptin resistance? But when I decided I needed to lean down, I practiced portion control and overtime my body adjusted to smaller servings. I am shocked sometimes when I feel nauseous after trying to indulge/binge, and I’m sensitive to sugar; I can’t handle things that are too sweet. Except m&m’s… my achilles heel.

    • Thanks for sharing and yes your body does get used to how much and how frequently you feed it. It adapts accordingly.

  • Jenny Hudson

    Excellent information about Leptin. See here for very fast and easy weight loss. http://www.amazingaus.com/best-foods-to-eat-when-losing-weight/

  • sakib800

    Hey Mike i remember a podcast from you where you mention how your actual Tdee is around 3000 but if you eat that much you get fat and then you state its probably becasue you have low leptin levels which “downregulates” your metabolism. and you eat around 2700 cals

    Could this also be the reason I cant seem to lose by last bits of fat? or could this be a reason why 12-10% tryng to go down to %8-9 is difficult?

    I mean if i eat lots of carbs and increase leptin will it better my fat loss?

    Becasue at the end if it comes down to a calorie defecit can leptin really make your tdee drop by like 400-500 cals?

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