My first 7-day blood sugar monitoring experiment

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As a dietitian in private practice who sees clients one-on-one to discuss personalised nutrition advice, I end up talking about blood sugar control a lot. That is because our blood sugar levels seem to affect us in many more ways than what we might think. From a clinical perspective, when someone says blood sugar, your mind immediately jump to diabetes (and I’m probably not the only one who’s thinking this).  However, our blood sugar levels seem to affect everything from our appetite, food craving, mood, sleep quality, and ability to lose weight. Blood glucose touches just about every cell in the human body. That means, when it runs awry, we can feel pretty awful in many different ways.

To further my understanding as a relentless health hacker and clinician, I have been wearing a continuous glucose monitor. This blog is a summary of my personal discoveries from this first week.

Also to clarify, throughout this blog I will be using blood glucose and blood sugar interchangeably. Glucose is a single molecule sugar and is the primary carbohydrate currency used by our body. All carbohydrate we consumed is shuffled around the body as glucose at some point in time.

High-intensity exercise has a huge glucose requirement

In the last few months of recently joining a CrossFit gym the newly-introduced very high-intensity exercise has seriously pushed my fitness. I certainly saw the extremity of high-intensity training in my glucose responses giving me a weekly high of 9.7 mmol/L.

In the session on the 30th, we did 25 min of mostly cardio with many burpees and 3 km running in total. Looking at this huge glucose spike, I feel totally amazed at the human body’s capacity to respond to extreme physical demand. Humans are primed ready to run. We have these awesome hormones called adrenaline and cortisol which give us the capacity to be alert and ready to flee from predators on demand. Despite showing up to training fasted that morning my body had the reserves to show up as needed.

High-intensity exercise also has a very powerful residual blood glucose lowering effect. I had consistently more readings in the red zone (below 4.0 mmol/L) in days post CrossFit. I also felt more hungry. Exercise stimulates non-insulin dependent glucose transport into muscle tissue. This means when you train hard, your muscles are primed for soaking up carbs and glucose from your food.

The major demands for the new style of training I’m doing has been a serious shock to my body. Especially on the 30th of November, after the ultimate peak-level effort training session, I crashed near the end of the day hitting a pre-dinner hypo of 2.7 mmol/L – we call anything a hypo if it comes with symptoms such as anxiousness, blurry vision, cold sweats, panic, and hunger. For future training session of this intensity, I’ll be aiming to include more post-workout carbs to prevent any hangriness.

crossfit glucose

Alcohol lowers bloods glucose levels

Big surprise here! Alcohol actually doesn’t tend to spike blood glucose levels. In fact, while red wine has less carbs than a white, they might both leave you with the same blood sugar levels. I’m not going to claim to understand the physiology here but I imagine alcohol has some impact on the liver’s role in glucose release (glycogenolysis). Maybe the liver is too busy trying to detoxify alcohol that it can’t be ‘effed keeping blood sugar levels under control.

After a few sips of white wine before dinner, I saw my BGLs trickle down from the high 3’s to low high 2’s mmol/L. This is might help to explain why we crave carbs when drinking.

About fruit

After seeing what fruit does to my glucose levels, I felt like it was a total waste of time snack choice. As one of the highest GI whole foods I eat on a regular basis, one orange or one apple spiked my glucose up to the 7’s. Within 30-minutes of finishing eating, my glucose totally dropped again to where they were before eating. This means, within 30 minutes of eating a piece of fruit, I was left feeling the same as before having a snack =  equally as hungry. This is why I usually advise when having fruit or simple carbs it’s best to avoid having them “naked” – always “dress up” your carbs with other fat and protein-containing foods such as yoghurt, peanut butter, or a handful of nuts.

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