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Avoiding “The Bonk”: 5 Tips for Dealing With Reactive Hypoglycemia [When getting the "sugar shakes" has nothing to d

Posted Sep 24 2013 1:02am


This morning dawned (?) dark, rainy and cold – the perfect time for my scheduled park workout! Because I’m bad at planning! After dragging myself out of bed at the crack of black and convincing my friend to as well, we did a quick half hour circuit of body weight exercises and sprints. It was one of those workouts that doesn’t feel too rough when you’re doing it but really takes a lot out of you, especially if you’re not used to high-intensity interval training. So when my friend texted me a half hour later saying she was shaky, couldn’t get warm and also couldn’t lift her arms over her head, I felt bad for not warning her about the possibility of getting the dreaded sugar shakes.

You know, how you sometimes get shaky, light-headed, nauseated, cold, and mentally foggy during or right after a workout? That completely miserable feeling like you kinda want to puke or die? Yep, sugar shakes. I’ve so been there. Which makes it sound like we’re sugar junkies jonesing for our next hit of the white granulated stuff (confession: I kind of am) but in reality something as simple as an early morning workout before breakfast can throw your blood sugar was all out of whack.

I used to get low blood sugar – or hypoglycemia if you want to get all technical about it – all the time. If you grew up in the 9o’s then surely you’ve heard of hypoglycemia as it’s the condition that killed Shelby (Julia Roberts) in Steel Magnolias and made me do my first-ever ugly cry in public. (Was that not the saddest scene ever done in a movie? I get choked up just remembering it! She was about to get married! Solidarity, Liz!) When you’re diabetic, having your blood sugar get too low can be fatal. Thankfully for the rest of us who experience a little hypoglcemia thanks to exercise or some other outside factor – called reactive hypoglycemia – it’s not usually deadly, just uncomfortable. And with a little planning the sugar shakes are totally manageable.

I’m not a great planner, remember? Let me back up.

I’ve always been a fainter. Thanks to a propensity for abnormally low blood pressure if I stand up too quickly, kneel down too long or lock my knees while singing just like my choir teacher always told us not to, I’ll hit the ground. The faint is over as soon as I’m down usually. So it’s really more like swooning?

My most spectacular faint was in college right after a swing dance competition thing (it was our first and if I remember correctly we really kinda sucked) and thanks to nerves – and let’s be honest, my raging eating disorder at the time – I hadn’t eaten anything all day and then we’d danced for 6 hours straight. I don’t remember all the details except that we were walking back to our car and I got dizzy and nauseous and sat down on the curb. I think they left me? And came back for me? Anyhow, I’d fainted clean out on the concrete. Next thing I knew I was at a gas station, my friend friend Janette was pouring orange juice down my throat and my other friend had confiscated my keys and had to drive us all home in my car.

Janette, who was majoring in nutrition, asked me if I was hypoglycemic. I had no idea. So I went to the doctor and after a blood test the verdict was that yes, I am more predisposed to it than most people (yay me!) as my normal blood sugar is 100 mg/dl which apparently is right on the border of low. Did I bother to learn about my new condition? Take steps to prevent it? Dump the stupid boyfriend who left me on the curb for my girlfriends and/or a scary murderer to retrieve? No, no, and I wish. For years afterward, I just kind of muddled through my “episodes” mistakenly carrying candy to fix them. That is, until I got into this whole health and fitness jag I’ve been on for the past 7 years. It turns out lots of people, especially us fit folk, are prone to episodes of low blood sugar and while it makes you feel like TOTAL CRAP, it’s fairly easy to prevent and remedy.

What Is Exercise-Induced Low Blood Sugar?

The primary source of fuel for our muscles is glycogen and when we exercise very hard or very long (or both), both our muscles and our liver – the storage of the all-important glycogen – get depleted. When you’re a little depleted you experience the symptoms I described above: shakiness, dizziness, disorientation, nausea, chills, fatigue etc. When you’re super depleted during an endurance exercise that’s when you  “hit the wall” or “bonk ” which is an utterly craptastic feeling as anyone who’s been there can tell you. I don’t know that I’ve ever felt worse in my life, frankly. In addition to the above, you may lose the ability to regulate your body temperature, vomit, faint, lose control of your bowels (oh yes), be unable to stand unsupported and have an irregular heart beat among other scary things.

This effect can be exacerbated by how well (or not) you fuel your workouts.

How to Prevent Low Blood Sugar*

As I understand it, our bodies store glycogen as fuel in our muscles and liver. When we need it, it is broken down into glucose (a sugar) and then metabolized into immediate energy via glycolisis. (I could be totally wrong – if I am, feel free to educate me in the comments and I’ll bump your explanation up here!) However, not all glycogen can be immediately accessed and so depending on how much food we’ve eaten, when we last ate and what we ate, we could have quite variable stores. What you want to avoid is the blood sugar roller coaster where you skyrocket your blood sugar up only to have it come crashing down shortly later, starting a vicious cycle.

1. To prevent this, eat small balanced meals every few hours. While I’m not a huge fan of the mini-meal mentality – contrary to popular belief, the research does not necessarily support this as a good weight-loss tool and it’s a pain in the butt to plan – if you’re prone to blood sugar swings this can help you stop the roller coaster. Also, emphasis on the balanced. Simple carbs like most processed foods (including, incredibly, whole wheat bread!) skyrocket your sugar only to crash 30 minutes later. Hello, afternoon nap.

2. Eat something about an hour before you workout and bring something to eat right after your workout. This last piece has been critical for me. If it’s an easy day, I don’t really worry about it but I’m lifting heavy or doing something high intensity, downing the protein/carb smoothie right after I finish is the difference between feeling like crap the rest of the day and bouncing right back. I can’t even tell you how much this has helped me.

3. If you know you will be exercising longer than an hour, it’s smart to bring something to refuel during. Sport gus (goos), gels, beans, blox and drinks are popular options. Or just bring candy. They’re basically the same as the “sport” stuff but way cheaper. (If you’re Gym Buddy Allison you stick a chocolate protein bar down your cleavage only to discover that when you most need it, it has melted into a pile of goo inside your top.)

4. The practice of “carb loading” before a race – eating a large amount of simple carbohydrates in the few days before the race in order to stockpile glycogen in the muscles – is controversial. I know a lot of runners that swear by the pre-marathon spaghetti feed but the research on its effectiveness is mixed,  possibly because many athletes do not do it properly . For myself, carb loading has never seemed to make much of a difference but I know people who swear by it.

5. Try intermittent fasting . It sounds counter-intuitive but abstaining from food for an extended period of time (usually 18-24 hours) every once in a while trains your body to be more insulin sensitive, which is a good thing as that means your body is learning to be more efficient at metabolizing your food. Insulin resistance is the precursor to diabetes and so IF can not only help prevent hypoglycemia but can also help prevent diabetes!

How to Treat Low Blood Sugar*

But what if you’re already in swoon city? Do not, I repeat, do not sit down on a concrete curb and wait for your friends to notice you’re missing. Actually, if you just have the sugar shakes taking a rest and eating something right away usually takes care of it in just a few minutes. If you’re really bad off, go for the straight sugar (that’s why diabetics carry glucose tablets… Shelby!!) But if it’s a milder case, something with some easily absorbed protein and carbohydrate works well. Chocolate milk has been shown to be particularly effective (although I gotta say that for me, after a long, hard workout milk does not sound at all good). Think of the kinds of things you see in the finishing race chutes: bananas, salted nut rolls, Muscle Milk, bagels etc. I also find it helps me to keep a sweatshirt handy, even on a warm day, as being cold and sweaty seems to make it harder for me to recover. I’ll warn you that if you’re pretty shaky you’ll likely feel pretty nauseous as well and eating will not sound fun. Do it anyhow.

If however, you are past shaky and all the way to sickville you need to get attention immediately. This is a hard call because from my personal experience, the mental disorientation makes it really hard to make a rational assessment of your situation. If you run with a friend, make a pact to look out for the other one. If you are in a race, there should be medic tents every so often and if you’re in doubt, go ahead and stop. But make a plan in advance of some way you can find help if you need it. Usually the support people will have you lie down, wrap you in blankets, and get you to eat or drink something. If you’re really bad off you may need to go to the hospital. That’s never happened to me (knock on wood) but I have heard of it happening to other exercisers!


From my experience, the best option is to plan ahead. Carry a few gels on you. Bring a protein shake to the gym. Be aware of what your limits are and what your body feels like when you hit them. Know what the sugar shakes feel like. A little advance planning is totally worth it.

Do any of you get the sugar shakes? Have you ever “bonked”? What’s your method for dealing with low blood sugar? And did anyone else ugly cry through Steel Magnolias?!

*All of this is based off of my own reading and personal experiences. I am in NO way a doctor, nutritionist, chemist or even all that smart-ist so if you think you are prone to hypoglycemia, please go see a medical professional. This is not meant to be medical advice.

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