Top 7 Weight Loss Hormones (And Where Keto Comes In)
Advanced Topics

Top 7 Weight Loss Hormones (And Where Keto Comes In)

Top 7 Weight Loss Hormones (And Where Keto Comes In)

Posted a year ago

Brian Stanton

Brian Stanton

Tony O’Neill, PT, DPT, MSc, RDN

Tony O’Neill, PT, DPT, MSc, RDN

Scientific Reviewer

Expert Approved

Our bodies don’t come with a “lose weight” easy button. Maybe in the year 2500, but not today.  

Nope. Bodyweight regulation is more complex than that, and much of this complexity comes from the chemical messengers we call hormones.  

Some hormones make you hungry, while others make you full. Some help you burn fat, while others promote fat-storage. And all of them, in one way or another, are influenced by your diet and lifestyle. 

In this article, we’ll review the most important hormones for weight loss—including how the Keto diet affects them. If you’re considering Keto, or simply want to know more about hormones and weight loss, keep reading. 

What Are Hormones?

Hormones are chemical messengers that tell your cells what to do. They patrol your bloodstream, always giving directions (burn fat, grow muscle, etc.) to different parts of your body. 

Where do hormones come from? From your glands.  

The adrenal glands make stress hormones, the thyroid gland makes thyroid hormones, and the pancreas makes your energy boss hormone, insulin. 

To be clear, these glands don’t just pump out hormones willy-nilly. They mostly take their directions from (you guessed it) other hormones!

It’s one big interconnected system. One hormone goes up, another goes down. 

Getting these hormones in the right balance is a big part of managing your weight. Let’s explore how these hormones work, and what you can do to improve your hormonal health. 

Top 7 Weight Loss Hormones

The following seven hormones factor heavily into body weight regulation. Wondering where Keto comes in? We’ll cover that too. 

#1: Insulin

Think of insulin as your energy storage boss. It tells your cells whether to store blood sugar as glycogen (stored glucose) or fat. 

When you eat a meal (especially a high-carb meal), your blood sugar rises, and you need lots of insulin to safely store that excess sugar. Lots of insulin, lots of energy storage. 

Problem is, your glycogen storage capacity in muscle and liver cells runs out quickly. After that happens, there’s only one place left for insulin to store the sugar: Body fat.[*]

So lots of insulin, in reality, means lots of fat storage. This is, in large part, why type 2 diabetics can’t stop piling on fat. 

Where does Keto come in? By restricting carbs, Keto helps keep blood sugar and insulin levels low. Only with insulin low can you burn (rather than store) body fat.[*

#2: Leptin

Meet leptin, your satiety hormone. By making you feel full, leptin prevents overeating, which makes it easier to maintain a healthy weight. 

Here’s how leptin works. After you eat, leptin is released from fat cells, then travels to a brain region called the hypothalamus.[*] When leptin hits your brain, you push back the chair from the dinner table. That’s enough.

But more leptin isn’t necessarily better. High levels of leptin generally indicate a condition called leptin resistance. When you’re leptin resistant, leptin doesn’t make you feel full anymore, and you subsequently overeat.[*]  

Where does Keto come in? Leptin resistance is caused by overeating.[*] (Often overeating carbs.)[*] By eliminating carbs and curbing your appetite, a Keto diet can help you stay sensitive to leptin.  

#3: Ghrelin

Secreted in your stomach and pancreas, ghrelin is your hunger hormone. It’s the yin to leptin’s yang. 

Ghrelin stimulates cravings, leptin satisfies them. Ghrelin makes you start snacking, leptin helps you stop. Ghrelin blocks weight loss, leptin facilitates it. 

Ghrelin sounds like goblin. That’s how you remember ghrelin is the “bad” one.  

When you eat, ghrelin falls and leptin rises. That’s why food makes you feel full.

To keep cravings under control, keep ghrelin under control. Sleep is one way to do that. You know that ravenous feeling after a night of sleep deprivation? Elevated ghrelin is behind that.[*]

Where does Keto come in? A high-fat Keto diet has been shown to prevent elevation in  circulating levels of ghrelin.[*] These hunger reducing properties, in fact, likely explain much of Keto’s success as a weight loss diet. 

#4: Cortisol

You’ve probably heard of cortisol. It’s the infamous “stress hormone”, released by the adrenals during times of, shall we say, anti-relaxation. 

Cortisol tells your body: Hey, times are tough right now. Time to activate survival mode.  

Survival mode means muscle is broken down, bone building halts, and blood sugar is dumped into circulation for easy energy.[*] While this is a necessary state for the body to achieve in brief periods of stress when quick action is required, it becomes problematic when you are chronically stressed for long periods of time.

Cortisol also puts the brakes on fat burning.[*] Yep, during stressful times, your body wants to store fat for later.  

Managing cortisol levels comes down to managing stress. This means getting enough sleep, exercising, and practicing stress-reduction activities like meditation. 

Where does Keto come in? Since cortisol increases blood sugar and insulin levels, it’s like Keto kryptonite. Yet another reason to get a handle on your stress. 

#5: Testosterone

Testosterone is the prototypical male sex hormone, but keep reading ladies. Believe it or not, testosterone is ALSO the most abundant sex hormone in the female body—even more abundant than estrogen![*]

Testosterone functions primarily as an anabolic hormone, helping you build muscle and bone. But testosterone is featured here because it also increases fat-burning.[*]

After age 30, testosterone levels begin to spiral downwards, especially in men.[*] To offset this decline, focus on the big three: Diet, sleep, and exercise.

Where does Keto come in? Keto may increase testosterone levels. In one study published in the Journal of Strength and Conditioning Research, researchers split 25 men into two groups—high-carb and Keto—then had them lift weights for 11 weeks. Afterwards, the Keto group had greater fat loss and higher levels of testosterone.[*]

#6: Estrogen

Estrogen is the Big Kahuna of female sex hormones. It governs a woman’s sexual development, fertility, and body fat partitioning.  

Strangely enough, estrogen has bidirectional effects on fat storage. On the one hand, it promotes the accumulation of subcutaneous, or “jiggly”, fat. But on the other, it prevents the accumulation of dangerous visceral fat around the organs.[*

The decline in estrogen after menopause (and associated visceral fat gain) explains why many postmenopausal women are at greater risk for metabolic problems like type 2 diabetes. There is no simple solution to this issue, but again: Diet, sleep, and exercise are always important for keeping your metabolism on point. 

Where does Keto come in? One study suggests that high-fat diets like Keto help to prevent weight gain related to this estrogen decline in post-menopausal women, thus preventing metabolic syndrome and type 2 diabetes.[*]

Another study suggests that Keto diets are beneficial to female fertility and sex hormones.[*

#7: Thyroid hormones

Produced in the butterfly-shaped thyroid gland on the side of your neck, the thyroid hormones T3 and T4 wear many hats in your body.[*] T3 and T4:  

  • Increase the rate at which you use energy (metabolic rate)
  • Build muscle
  • Strengthen bone
  • Regulate body weight

When someone has low thyroid hormones (hypothyroidism), they often have difficulty losing weight. And when thyroid function is restored, weight loss becomes easier.[*]  

If you chronically restrict calories, thyroid levels will fall, and your metabolic rate will decline.[*] The minerals iodine and selenium are also crucial for thyroid health. 

Where does Keto come in? A Keto diet often lowers thyroid hormones, but this isn’t necessarily a bad thing. The prolific researcher Dr. Stephen Phinney makes the case that a decline in T3 on Keto (in the absence of symptoms) likely represents an increase in thyroid sensitivity—or the ability of your cells to respond to thyroid hormones. 

Weight Loss Hormones Recap

Whew, that was a lot of info. Let’s recap, in the simplest possible terms, what these hormones do:

  • Insulin. Your energy-storage boss. Less insulin = more fat-burning. 
  • Leptin. Your satiety hormone. High-carb diets make leptin stop working. 
  • Ghrelin. Your hunger hormone. Keto reduces it. 
  • Cortisol. Your survival mode hormone, brought on by stress, that also promotes fat-storage.  
  • Testosterone. Fat-burning and muscle building. Keto may increase.
  • Estrogen. This female sex hormone tells fat where to go. Less estrogen = more visceral fat. 
  • Thyroid hormones. T3 and T4 keep your metabolism humming along.

Hope you enjoyed meeting your weight loss hormones today. If you have any friends that might want to meet them too, feel free to share! 

Comments 18

  • Tomatogirl

    Tomatogirl 2 months ago

    My body doesn't produce cortisol, I have Addison disease ,my adrenal glands no longer work so I have to supplement with 3 steroids. How does it affect me on keto?

    • malicent1

      malicent1 4 months ago

      how will having no estrogen effect keto

      • SuperMacadamia887959

        SuperMacadamia887959 4 months ago

        Thanks for sharing in a no nonsense easy to understand format! Great info!

        • Porshabert

          Porshabert 4 months ago

          I've been doing keto for a year just had blood work done and my thyroid meds went from 175mg to 150...I'm thinking that's a good thing:)

          • Barrowgirl73

            Barrowgirl73 6 months ago

            Testosterone?! Who knew🤷‍♀️ I knew we had it but not like that.

            • Nom72

              Nom72 6 months ago

              Very interesting 🤔

              • thunder5758

                thunder5758 6 months ago

                Great overview

                • Bonz

                  Bonz 8 months ago

                  Hi. Any suggestions on insulin resistant which I have been told I have when I’m sleeping

                  • Millie

                    Millie 8 months ago

                    Concise and helpful. Thank you!

                    • 2BTru2Me

                      2BTru2Me 8 months ago

                      👍🏻 TY!!

                      • lorettalucas1e5d

                        lorettalucas1e5d 8 months ago

                        Excellent information. I'll do further searching for post menopause weight loss.

                        • tjsych@gmail.com

                          tjsych@gmail.com 8 months ago

                          Very helpful thank you

                          • DMGastley

                            DMGastley 8 months ago

                            LOVE this article! I've been trying to explain to everyone why I can eat so much fat and still lose 260 pounds!!

                            • IneffableArugula686104

                              IneffableArugula686104 5 months ago

                              Omg you have lost 260 lbs

                          • lheaslet

                            lheaslet 8 months ago

                            All good to know!

                            • Reeniebh

                              Reeniebh 8 months ago

                              Wow. Reading this many times!

                              • StellarMacadamia862982

                                StellarMacadamia862982 9 months ago

                                Very informative

                                • UpbeatCauliflower144129

                                  UpbeatCauliflower144129 9 months ago

                                  Good information 👍🏼