How Insulin And Cortisol Affect Your Body Composition

By Dr. Brooke Kalanick

Talking about insulin and cortisol—or in simpler terms, carbs and stress—has finally become part of the conversation about body composition in earnest. We’ve begun to recognize that getting lean is not as simple as “calories in versus calories out.”

insulincortisol1-woman-fitbit-450x340Now, the argument has shifted to, “Which matters more, calories or hormones?”

Is your biggest battle with calories or with hormones? Some will argue to their grave that a calorie is a calorie is a calorie, and that so long as you burn more than you eat, then you’ll lose weight. Others believe you can forget about calories, eat all of the bacon, skip the bread, and you'll see big changes. So which one truly matters more? It’s funny how this polarity of ideas always rules the Internet. Of course, the answer is never that black or white.

Where changing your body composition is concerned, the right answer is that both calories and hormones matter. They both matter, big time.

There is no denying a fundamental law: a calorie deficit needs to exist in order for your metabolism to dip into stored energy. But how you get there—how you create that deficit and how you play with your metabolism day after day to keep it from adapting and slowing down, not to mention manage cravings, energy, and appetite surges that can occur when you blindly cut calories—that has everything to do with hormones.

If you’ve spent any time reading about this stuff on the Internet, surely you’ve seen many an expert preach that one particular hormone is “the one.” The Big Mama. The only one that matters. Just manage this one hormone, and you’re golden.


For a while that one hormone was insulin. Then it was leptin. More recently others have taken center stage. The thing is, they all matter. Everything from commonly known hormones like insulin and cortisol, down to immune-signaling molecules that you’ve probably never heard of, like Il-6 and Il-15, play a role in your body composition.

One thing is certain: you can’t be expected to know how to manipulate every metabolic messenger with every bite of food you take. In my office, we’re down to the nitty gritty, shifting immune systems, sprucing up more subtle hormone activity. However, for most of you reading this, simply having a better understanding of two of your main metabolic hormones—insulin and cortisol—will be tremendously helpful toward reaching your physique goals in a healthy way. Here’s why:

  • You have a lot of control over these two hormones. While you likely can’t move the needle a whole lot on your thyroid with food alone, or you may not understand the nuances of IL-6 enough to tweak that in your favor repeatedly, but you do know how to mediate your body’s stress levels. You know that by taking time to de-stress, by getting enough sleep, and by eating certain foods, you feel better and less stressed. That’s you managing your insulin and cortisol levels.
  • These hormones talk to you all day. They speak to you via appetite, cravings, energy, and sleep... all dang day! If you can listen and work with those signals, you’ll be able to adjust your nutrition and training in a way that makes these hormones happy. I like to use the acronym ACES: appetite, cravings, energy, and sleep What goes on with these four things is basically your hormones talking. Listen up!
  • Insulin and cortisol influence all other hormones to such a great degree that if they aren’t in balance, your efforts to boost progesterone or lower estrogen dominance, or even effectively utilize your thyroid prescription, will be only minimally effective.

Yes. Thyroid, estrogen... they all matter, just like calories matter.

If you can understand how to handle insulin and cortisol and make them work for you, then you’ll be better able to manage your food intake without experiencing crazy cravings and hunger, ultimately improving your body composition. Plus you’ll balance a number of other hormones at the same time to achieve better overall health.

Now, insulin and cortisol aren’t new kids on the block. This is probably the hundredth blog you’ve read on how stress can lead to excess body fat in your midsection. You’ve tried to cut carbs to lose weight. The problem is that while “Carbs Are the New Calories” and “Stop Stressing and Lose Weight” are catchy headlines, it’s led to a lot of misunderstanding about how these two hormones actually work—more importantly, how they work with other hormones. This article will clear all of that up. Don’t be surprised if you stumble across a few “a-ha!” moments about your own metabolism in the process.


Insulin is an anabolic hormone. That means it builds–both muscle and fat tissue. It is, above all, a storage hormone. It stores sugar, vitamins, and fats for later use. You release insulin in response to any rise in blood sugar, whether it’s due to eating or to stress.


This is typically where all understanding of insulin stops for most people: carbs lead to weight gain. But it’s not that simple.

While insulin is secreted most significantly when eating carbohydrates, it is also released when you eat protein (however protein also releases the fat-burning hormone glucagon). Indirectly, insulin is released when eating fat as well, via the hormones ASP (acylation stimulating protein) and GIP (glucose-dependent insulinotrophic peptide). This is important to note because it’s a common misconception that protein and fat are “free foods” and that you only need to worry about carbs when it comes to insulin.

For those of us with PCOS (polycystic ovary syndrome) or insulin resistance, going low-carb often doesn’t solve all our body composition challenges. Some of us tend to overdo it with protein, and when it comes to high fat + high carb meals, we all run into trouble.

In addition to storage, insulin also plays a role in helping you feel full or sending satisfaction signals... at least in a perfect world. After all, you release insulin when there’s plenty of fuel in your bloodstream and you should, in fact, feel full. However, because of its interactions with other hormones like cortisol, ASP, and GIP, combined with our modern lifestyle of too much food, too much sugar, too much booze, and too much stress, this aspect is often nil for anyone who struggles with their weight or hormonal balance.

What Is Insulin Resistance?

Insulin resistance occurs when your cells do not respond appropriately to insulin’s messages. Your body becomes less efficient at shuttling nutrients into your cells for use, so when you do eat carbs, protein, or fat, you experience an exaggerated response to any rise in blood sugar. It’s sort of like being at a loud concert and having to yell at your friend until they eventually hear what you are saying.

This inefficiency creates prolonged blood sugar elevations and excess insulin secretion and can produce a low blood sugar effect as a rebound after insulin’s signal finally gets through, leaving you hungry and craving the carbs that got you in this predicament in the first place. The more often this happens, the more insulin resistant you become.

Why does this happen? Usually you get here by chronically over-carbing, over-eating, or over-stressing (which could equate to under-carbing, under-eating and over-exercising, among many other stressors).

You can eat your way, or stress your way, to insulin resistance.

This is beyond the scope of this post, so I’ll be brief, but understand that while insulin sensitivity is typically thought of as “you have it or not,” in actuality, it’s not so simple. Insulin sensitivity changes in response to exercise, and varies greatly from person to person, and even from tissue to tissue within the same person. For example, fat, liver, and muscle tissue can have varying insulin sensitivities. This is why women with PCOS (a condition that has insulin issues at its core) don’t all look the same or have the same difficulty when it comes to altering their body composition. Some of us have more sensitivity when it comes to fat tissue, and others to muscle tissue, making PCOS very misunderstood.

It’s also important to note that specific components can make some people, myself included, more prone to insulin resistance. While it can be managed, a poor diet or high stress will always make things worse for people who have a genetic predisposition for insulin resistance. For example, if I start eating cereal for breakfast, sandwiches for lunch, and pasta for dinner, I guarantee you that my currently well-managed insulin resistance would worsen, my face would be full of breakouts, my cycle would get all messed up, and the pounds would pile on in a hurry.

However, for those who stressed their way to insulin resistance, management tends to happen more easily. Ah, stress… that brings us to cortisol.


Cortisol is a double-edged sword. Secreted by the adrenal glands, our main stress hormone has a couple of jobs including raising blood sugar. Cortisol is vital for life, necessary for fat burning, and is even anti-inflammatory in small doses. Yet, on the flipside, when your body experiences it in too-high doses, it can cause an increase in body fat, slow the metabolism by affecting thyroid hormone levels, lead to inflammation, induce cravings, and create a big metabolic mess.


Cortisol is a perfect example of a hormone that can behave differently depending on the amount and frequency with which your body releases it, and perhaps even more importantly, how all of your other hormones are working and how much of them are present. It’s a big mistake to say things like, “cortisol causes belly fat.” It doesn’t happen in isolation like that.

How You Burn and Store Fat

Part of the problem with many articles about hormones is that they make it seem so straightforward. It seems like a hormone does this or that, and that it always works that way. It doesn’t. Hormones are very much an orchestrated process, and they all work together. What’s more, they may behave slightly different depending on your unique metabolism. Before you can really understand how to manipulate hormones like insulin and cortisol, it’s important to understand the basics of how fat gets stored and how you bring it out of storage to use for fuel.

The first key player to know when it comes to fat storage is LPL (lipoprotein lipase). Simply put, LPL is the fat storer. It makes triglycerides (a form of fat) and puts them in a fat cell for storage. Another important player is HSL (hormone sensitive lipase) which lets that fat out. When it comes to fat burning, insulin and cortisol in the process depends on how they interact with these LPL and HSL.

Here’s what happens:

  • Insulin turns up LPL to make more fat/triglycerides.
  • Insulin puts the breaks on HSL, slowing down your ability to release stored fat into your bloodstream.
  • Next, insulin slows down the ability of an enzyme called CPT1 to break down fat in your bloodstream to turn it into energy.
  • During short periods of not eating (for example, during the night and between meals) as well as with short duration, high-intensity exercise, cortisol will turn on HSL, triggering fat release. It does this with help from growth hormone and adrenaline.
  • When cortisol and insulin are around together, it causes an exaggerated effect on LPL (fat storing) and insulin hinders HSL, overriding what cortisol is trying to do (release fat for burning).
  • Chronically elevated cortisol will make you more insulin resistant....and on and on we go.

You can see, it’s not that these hormones have different effects or varying intense effects depending on which other hormones are also present. Some of these hormone, in combination, make managing your body composition much harder.

Insulin and Stress: The Absolute Worst Combo

As you just read, the storage and release of fat are both affected by insulin and cortisol. When the two are elevated together, it makes storing fat easier and burning fat harder. This combo of insulin and stress can come about in many ways. The insulin issue doesn’t begin and end at carbs, and the cortisol issue doesn’t begin and end at stress. How these hormones uniquely interact in your body really tell a bigger story. But wait, there’s more.

Chronically elevated cortisol can lead to loss of muscle—your metabolic motor—slowing down your metabolism.

It also adds to insulin resistance, making it even harder to see progress. This insulin-cortisol fat-storing combo is especially tough on fat cells around your midsection (what some people refer to as “belly fat”). To complicate things further, these fat cells can actually make some cortisol of their own.

To complicate things even further, yet another stress hormone is at play here: NPY (neuropeptide Y). NPY is part of what triggers you to eat when you’re stressed—along with cortisol’s effect of making you crave high-fat and high-carb foods. NPY also leads to fat storing.

Sigh... Problems with both of these hormones greatly impact your thyroid, and on and on we weave this messy web.

What to Do

Eat as often as you need to, but not so often that you are grazing.

This can be tricky and totally unique to you, so use ACES (appetite, cravings, energy, and sleep) to guide you. Ask yourself: “Am I having increased appetite between or after meals?” “Am I having sugar cravings between or after meals?” “How is my energy between meals or immediately after eating?”“Am I falling and staying asleep easily?” As you ask these questions, keep in mind that symptoms between meals are related to lower blood sugar problems and symptoms immediately after eating are related to insulin resistance problems.

Eat to your unique carb tolerance.

This means finding out how much of what type of carbs you can eat while keeping your ACES in balance. For example, I know that I can eat an entire apple, but if I eat as little as four bites of a sweet potato, I’m craving the rest of that sweet potato. And if I finish it, I’ll be asleep on the couch.

Don’t overeat.

Too much food in general will tax your blood sugar balance. It takes practice to start sensing when you feel 70 to 80 percent full (satisfied and comfortable, but not stuffed), and when you’re actually hungry. Don’t worry if you can’t do this yet. The more in balanced your hormones get, the more in tune you’ll be. For now, eat slower, giving your body time to talk to you. Try taking 20 minutes to eat a meal; that’s about how long it takes for your hormones to tell your body that you’re full. It will feel like forever at first, but stick with it and you will notice a big difference in your health.

Steer clear of fat + sugar meals.

This combination makes the biggest mess of insulin and creates the strongest fat-storing message. When dining out, opt for veggies and protein, assuming the meal has more oil or butter than you’d use at home. Skip the rice, pasta, bread, and booze in these situations.


Watch out for fat + sugar foods like bagels with cream cheese, chips and guacamole, and desserts like cheesecake and ice cream.  I’m not saying you should never eat these—not at all—but if this is your go-to treat, be mindful that it may be hindering your progress if you’re insulin resistant.

Eat loads of veggie fiber and adequate protein at each meal.

Start with two to three handfuls of veggies and at least four ounces of protein. Four ounces of protein typically looks about the size of a deck of cards or the size of your palm.

Manage emotional stress in whatever way works for you.

This is a biggie. We all get here in our own way. For me, it takes many, many things to control my emotional stress. I have to eat well and get enough sleep. I have to take my supplements. Most importantly, I have to stay mindful of the kind of woman I want to be.

If you don’t know where to begin, this simple breathing tool lowers cortisol instantly: Breathe in for four counts and exhale for six to eight counts. I use this about a hundred times a day! My life is busy and can be stressful. That’s not changing. The only thing I can change is how I respond to that stress. This tool really engages the parasympathetic nervous system, pulls me out of “fight or flight”mode, and allows me the space to act how I want to, instead of in a frenzied default.

insulincortisol2-woman-sleeping-450x340Get enough sleep!

Simple enough, right? In theory, yes. In practice, most of us struggle with this. Get to bed early with a pleasure book, not a thriller or work-related book that’s sure to get your mind going. Be sure you have a dark, cool room. By all means, if you have trouble falling asleep or staying asleep, get some help! Nothing is worth more to your health (and your goals!) than sleep.

Manage inflammation.

Discover and avoid any foods that you know trigger allergies and sensitivities. Get help with your autoimmunity (e.g. Hashimoto’s). Heal long-standing injuries. Avoid overtraining or over-exercising. Get enough rest and don’t drink too much wine. Adequate omega-3 and supplementing with turmeric and resveratrol can also really help. Before taking any supplements, it is recommended that you consult with your healthcare provider for appropriate dosing and to make sure there are no interactions with any existing medications you might be taking.

Don’t overtrain—especially with long-duration cardio.

insulincortisol2-woman-training-450x340If you love activities like spinning and running, you don’t have to never do them again, but if you’re struggling to lose fat, are noticing less motivation to work out, or feel generally achy and inflamed, it’s time to change things up.

Be sure your training plan is well-rounded and includes adequate rest between training sessions. If it currently includes no weight training and five spin classes, make some changes to balance things out. If it’s all heavy weight training and sprints, balance it out with some lower-intensity, restorative activities like walking and yoga.

A Final Word on Hormones and Body Composition

With all of this talk on insulin resistance, cortisol, and fat, it’s important to remember that hormones are not the problem. They are the solution! Hormones can be your biggest ally in achieving biological balance, managing your body composition, and enjoying better overall health. Treat them with the respect they deserve, and they’ll treat you in kind.

Get in the best shape of your life—for good.

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About the author:  Dr. Brooke Kalanick

Dr. Brooke Kalanick earned her Doctorate in Naturopathic Medicine from Bastyr University. Known as “The Hormone Whisperer,” Brooke's balanced approach to health, using both conventional and alternative therapies, allows her to successfully treat patients with Hashimoto’s Hypothyroidism and PCOS as well as other female hormone imbalances. Learn more about Dr. Brooke on her website and connect with her on Facebook and Twitter.

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