This is your body on sugar | the science behind food cravings

As a fitness professional, I hear a lot of food “confessions”.

science behind food cravings

Stock photo purchased from DreamTime

Here’s just a sampling of this week’s shares (names omitted and comments paraphrased to protect the innocent…);

“I have no self control when it comes to chocolate”

“Why can’t I stop at just one cookie?”

“I get the worst cravings for PopTarts just before I get my period”

“Gotta have that mid-afternoon coffee and donut to make it through the day

“I looked down from the TV to find an empty bag of chips on my lap. I don’t even remember eating them”

Frequently, these admissions are accompanied by feelings of guilt and shame and promises to exert more willpower in the future.

The thing is, willpower alone doesn’t usually lead to success. In my experience, willpower goes a lot further when one understands the underlying cause of the behaviour. And when it comes to food cravings, it’s all in your head.

Your brain that is. Your brain and the way your hormones communicate with it to direct your thoughts and actions.

The Science Behind Food Cravings

A long time ago human diets consisted primarily of plant matter and a little animal protein. Sugar, fat and salt were fairly rare commodities, although required for growth, reproduction and survival. Hence, human brains became wired to reward behaviours that resulted in the consumption of these scarce nutrients.

Not such a bad thing when sweet, fatty and salty were REAL foods (fruit, wild game, vegetables, seaweed) and difficult to come by.

Fast forward a few thousand years. The same reward circuitry exists, but the sweet, fatty and salty options available to us today are stripped of nutrition and readily available.

Think about eating something sweet, fatty or salty and the reward centre of your brain releases the pleasure-seeking hormone dopamine. Dopamine gets you excited about the possibility of eating a donut and motivates you to drive to the donut shop.

Eat something sweet, fatty or salty and your brain releases endorphins; opiate-like hormones that provide emotional relief, release stress and generally make you feel good.

science behind food cravings

Birthday cake makes me happy!

Repeat the ‘anticipation-satisfaction’ cycle a few dozen more times and presto, you’ve created a habitual response; the automatic craving for a specific food in response to particular triggers.

But it gets worse. In addition to stimulating the pleasure centres in your brain, sugar also triggers a cascade of hormonal responses in your soma.

Eat something sweet and your pancreas release insulin, a hormone that tells the cells of your liver, muscles and adipose tissues to store energy for future use.

If the sugar load is light and your body is sensitive to insulin, your pancreas will release just the right amount of insulin to return your blood sugars to their normal, healthy range. Since elevated insulin levels also have a satiety function, you’ll probably feel satisfied with your meal and leave the table without feeling hungry.

If the sugar load is heavy but infrequent your body’s insulin response will not be sufficient to remove the excess sugars from the blood and much of it will be stored as fat. As fat levels rise in the body, fat cells release leptin, a hormone that tell your brain that you’re “fat enough” and it’s time to eat less and move more.

If, however, the sugar load is both heavy and chronic (as it is for many modern humans) three very bad things happen;

(1) your body relies almost exclusively on sugar for fuel (fat stores go untouched)

(2) your brain stops hearing the leptin message (a condition known as “leptin resistance”) and continues to seek out sweet and fatty foods because it thinks you’re not fat enough

(3) your cells stop hearing the insulin message (a condition known as “insulin resistance” or Type 2 Diabetes) so your pancreas produces more insulin than necessary to remove sugar from the blood, thereby leading to blood sugar crashes and intense cravings for foods that will rapidly increase your blood sugar level (exactly the foods that caused the problem in the first place)

The only way to break the cycle (and undo the hormonal and metabolic damage) of cravings and addiction is to drastically reduce your intake of the offending foods; cookies, chocolate, chips and baked goods (to name but a few).

Now that you understand the science behind food cravings (the WHY), you’ll probably want some suggestions as to HOW to break the cycle. Because this post is too long already, I’ll keep you hanging until next week…

In the mean time, please check out this post on ‘trigger foods’ and share your tips and tricks for overcoming food cravings in the comments section below!



  1. I stopped eating most sugar years ago for the simple reason I FEEL LIKE CRAP (technical term) afterward.
    There was no way around it for me.
    Your use of the word CHRONIC is so very eyeopening though as we rarely (I rarely?) apply that term to FOOD.
    Miz recently posted…YES! Day.My Profile

    • Yes, for so many people it IS chronic! If you eat at restaurants or live on processed foods you’re definitely getting way more than is healthy. Agree with your technical terminology!

  2. “Eat something sweet and your pancreas release insulin, a hormone that tells the cells of your liver, muscles and adipose tissues to store energy for future use.”

    What many people don’t realize is that when they eliminate sugar, but use artificial sweeteners as a replacement, the pancreas can’t tell the difference in the beginning. The Pavlov’s dog response. Eat something sweet — even if it’s not sugar, and the body secretes insulin anyway (many studies support this). Then, with no real sugar, the body craves real sugar to offset that insulin response. And then people feed those cravings.

    One more reason why using artificial sweeteners is a bad idea — as a replacement to real sugars.
    Contemplative Fitness recently posted…The math of a mile…My Profile

    • Bang on! Fake sugars just don’t trip the satiety button so we keep eating because our body (rightly) knows that we haven’t ingested anything it can use for fuel.

      As far as real vs fake sugars go, I trust nature more than I trust chemists…

  3. Fantastic post, Tamara. I cover the insulin response and fat storage in my sugar detox workshop, and am always surprised how many people have no idea what is going on inside our bodies- it’s really valuable info to help us make a change!
    Laura @ Mommy Run Fast recently posted…Fall 5 and 10 September Recap and WinnersMy Profile

    • Thanks Laura! I’m a firm believer in the idea that knowledge is power. The more you know about the way your body works, the easier it is to make major lifestyle changes. So many people don’t seem to want to believe, though…

  4. Great post, with the cascade of events super well explained. My soma needs to quit listening to any sugar that makes its way past my brain and into my mouth.
    KymberlyFunFit recently posted…Sleep – How it Affects Your Weight, Brain & SkinMy Profile

    • Why thank you my friend! Such a lot of information to boil down into a few paragraphs without losing the gist of the argument. Hence the part 2…

  5. Great post. Sugar is my greatest challenge. I am a true addict. I quit, feel amazing, say I will never go back and then I have a bad day and reach for the chocolate. It is horrible cycle. For me when I quit, I have to go cold turkey (no fruit boo hoo) for about 1 week or so. I can then bring the fruit back in but I need to get past the cravings from the artificial stuff.

    The only alternative sugar that doesn’t spike your insulin is stevia.
    Stephanie Robbins recently posted…Affiliate Labor Day Deals with Robbins Interactive ProgramsMy Profile

    • I didn’t know that about stevia, Stephanie. However, even if it doesn’t spike insulin, it also doesn’t produce feelings of satiety (which is what needs to happen to stop overeating). My other concern with it is how concentrated the sweetener is; instead of re-training our palates to accept ‘less sweet’, it actually makes us think that naturally sweet foods aren’t sweet enough…

  6. This is an area in which I have a lot of interest. The food industries understand this science, and they use it well to keep us eating their products. The right combination of sugar, fat, and salt triggers the feel-good centers of our brain. And once that’s triggered, who doesn’t want to experience it again? And again, and again…

    Great article!
    Carrie Rubin recently posted…I’m Back… And I’m Bringing ‘Doctor Sleep’ With MeMy Profile

    • Oh Carrie, thanks for your comments, here and on Twitter this afternoon. It certainly isn’t coincidence that the food industries have figured it out. I’ve started reading some of the food psychology literature too and it’s FASCINATING.

  7. Great post Tamara – I am sure that was me before I lost weight young but got more knowledgeable on food in my 30’s. I am lucky that I have what they call good willpower or whatever word you want to use since I was able to manage it all even though I wanted it….

    I have my sugar things but not a ton like many. I also use artificial sweeteners & don’t have the issues many have with them but again, that may just be me able to manage myself – I just don’t know cause I have been at it so long…

    I am a balance in life person & I get that some can’t do that yet BUT if I avoid it all, I want it more! 🙂 Learned that the hard way!!!

    Looking forward to the continuation…
    Jody – Fit at 55 recently posted…Gratitude Monday & FAMILY! Birthdays too!My Profile

    • Thanks Jody! You have done (and continue to do) what we all need to do; be the detective. Figure out what works for us and our bodies and commit to doing it for the rest of our lives!

  8. This is a fantastic post Tamara. I know that I need to better manage my sugar cravings. It’s definitely a challenge. I have tried to do one week sugar detoxes but I always seem to get derailed mid-week by stress. That’s my biggest trigger. Can’t wait to read the next post!
    Christine @ Love, Life, Surf recently posted…16 Things I Learned on Summer Vacation (+ pictures)My Profile

  9. Great post!

    I definitely feel a lot better without sugar. I do use a little stevia once in a while but really limit it as I don’t want to constantly want sweet things.
    Andrea@WellnessNotes recently posted…Weekend Fun and a New CookbookMy Profile

  10. Is it weird that I have no self control when it comes to spaghetti squash and salmon? ah ha ha ah ah!
    GiGi Eats Celebrities recently posted…The Pig of the Fish WorldMy Profile

  11. I cut out junk from my diet years ago and found the only way was cold turkey. I hate being a slave to anything!
    Suzanne @WorkoutNirvana recently posted…How Candy as a Reward Degrades Healthy Nutrition in SchoolsMy Profile

  12. Love this post. People think I’m crazy when I say you can get addicted to sugar. But it is TRUE.
    calee recently posted…Fitness Friday: Best Body Bootcamp Week 1My Profile


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