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Everything I learned from wearing a continuous glucose monitor
Insights for a Healthy New Year
It is no secret that I follow and endorse a moderately low-carb way of eating, I even wrote a cookbook about it! But the recent explosion in the availability of continuous glucose monitors (CGMs) had made me curious to validate these choices again, for myself. The urge to see those blood sugar spikes that I have learned occur in theory play out with real-time data was hugely compelling. So I took the plunge, purchased a Levels CGM and decided to put recipes from my cookbook to the test, comparing them with their high-carb alternatives.
If you’re asking, wait, what’s a CGM - here’s a nice primer.
So what’s a healthy range for blood sugar? While this can vary, I quote the Levels team here - glucose rises and falls are normal and expected when we go about our day. But what we want to aim for is low glycemic variability, i.e., flatter valleys and low rolling hills, and not jagged peaks and sharp ravines. Frequent blood sugar spikes and associated surges of insulin (outside of making you feel crappy when you crash) can eventually cause insulin resistance , which has been deeply linked to type 2 diabetes, heart disease, PCOS and even brain disease.
I designed a series of crude experiments in the vein of A/B tests. My scientist dad has cautioned me against calling them real experiments as they didn’t have full scientific rigor! So I begin with the caveat this was a best efforts trial: while not conducted to laboratory precision, I have done my best to set up the tests under similar conditions. The compared foods were eaten in similar quantities and around the same time of day. I have tried to present the results without being alarmist, and I hope you will take away the big picture.
Bear in mind that this is a snapshot of one individual over a 14 day period. My own results may vary at a different time and yours may look quite different as well - carbohydrate tolerance can and does vary. And glucose is an important biomarker but by no means does it present the full picture. I could drink a gallon of vegetable oil without it affecting my glucose but that doesn’t mean it’s good for me.
I encourage you to read the full post - there are many nuances.
I tried 3 types of bread: a sourdough from my favorite bakery, a ubiquitous supermarket multigrain sandwich bread and the Zucchini Bread from my cookbook. The recipe was a basic toast (2 slices with butter), cream cheese and tomato.
Much to my dismay, my favorite sourdough spiked me the highest, over 80 points! The Levels app rubbed it in by showing me an animated airplane whooshing up to the sky.
The multigrain bread was high as well, but lower than the sourdough at about 60 points.
My Zucchini Bread performed admirably, creating a gentle rise of 25 points and I patted myself on the back.
To be honest, I was expecting the multigrain bread (typical garden variety processed multigrain from the supermarket) to do worse, but it did contain 3g fiber per slice. The sourdough was made with all-purpose flour which is mostly starch. However, the sourdough fermentation process should have broken down some of the starch, which is why I was expecting it to be a medium-glycemic load.
Does that mean that the multigrain is better? I’m not so sure - a closer look at the ingredients reveals several unpronounceable ones, including genetically modified soy and wheat. The sourdough had 4 ingredients - flour, water, salt and yeast. If my Zucchini Bread wasn’t around, I would rather pick the sourdough and eat a single slice, accompanied by more protein and green veggies. I do want to try a whole grain sourdough next and see how it does, but for now the Zucchini Bread will do, thank you very much!
Here was my litmus test, as cauliflower rice is a staple in my freezer! I compared white Basmati rice, quinoa and cauliflower ‘rice’. The recipe was a simple vegetable fried rice.
White rice brought back the tiny Levels airplane, spiking a dramatic 80 points! This was expected but nevertheless disappointing. Put it down to wishful thinking from a South Indian!
Quinoa created a medium-high spike of 60 points, reinforcing the importance of that fiber.
Cauliflower rice was smooth sailing at a 12 point gentle rise (go caulipower!). I knew there was a good reason to dedicate an entire chapter to cauliflower rice in my cookbook!
Well, that cauliflower rice is gonna stick around in my freezer. I actually love it and have found it to be a really great carrier for any flavor. I did find the quinoa spike to be quite high though, even when accounting for the fiber. It was an important reminder that grains, even whole, are a very dense source of energy and portion control is important. White Rice, I’ll see you when I’m looking for a treat.
P.S. I did try white rice with dal (cooked lentils) for a different test, and that flattened the spike materially (still high, but no airplane). F-I-B-E-R, you guys!
Pasta time! I was really curious about this one - I compared a regular spaghetti (all-purpose flour) to one of the lentil pasta varieties I’ve been enjoying, and of course, to zucchini noodles. The recipe was a basic pasta with tomato sauce and parmesan cheese.
Regular pasta was high, as expected, spiking a solid 60 points.
The lentil pasta was significantly lower, spiking 20 points.
The zoodles did well, they are 90% water after all! I’m guessing the tomato sauce added the carbs to that meal :)
The fact that white rice and bread spiked me so much higher than pasta was surprising to me. I can only speculate here without more tests - perhaps I’m half Italian, or more realistically, perhaps the fact that we (or I, at least) tend to cook pasta with lots of olive oil and a generous amount of cheese helped to flatten the curve here. Fat helps blunt those glucose spikes.
The lentil pasta was quite a revelation - this particular brand has more than double the fiber of regular pasta and tastes pretty good, even my toddler will eat it. I guess we’ve found a winner in our home.
Store-bought smoothies (or smoothie bowls) tend to be sugar bombs. Even when you add protein, they rarely have enough fat or fiber to balance your blood sugar. Here I compared a store-bought strawberry-banana smoothie with an added scoop of protein from a local chain, to a similar smoothie I made at home, adding Greek yogurt, nuts and chia seeds. I considered a comparison with my cookbook but ruled that out as I thought it unfair to the store-bought smoothie (my book has only savory smoothies).
The store-bought smoothie spiked me over 50 points. It also left me hangry an hour later.
My home-made smoothie created a gentle spike of 10 points and sustained me until lunch.
Sugar is sugar is sugar, even when it comes from fruit. When we blitz fruit into a smoothie, it alters the nature of the fiber to render it largely powerless. So it’s especially important not to overdo the fruit and add enough healthy fat and fiber to balance the sugar - nuts, flax and chia seeds, full-fat Greek yogurt are all winners. Try making your protein smoothies at home (a mental reminder to myself to publish my smoothie formula some day).
Now now, did y’all skip down to this one? I was excited for this test as the Hazelnut Brownie from my cookbook is one of my most craveable recipes. I purchased a brownie from my local bakery and set out to do the test as an afternoon snack, about an hour after lunch.
The store-bought brownie spiked me about 50 points, which was hardly a shocker. Honestly it was too sweet for me so I probably ate a little less than someone with a sweet tooth would.
My home-made brownie from the cookbook created a gentle spike of 10 points and even earned a perfect score on the Levels app. I knew this one was a winner!
The store-bought protein smoothie spiked my blood sugar just as much as the store-bought brownie did! I think this really just goes to show how so many foods marketed and perceived as “healthy” are not any better for you than dessert is.
My home-made brownie from my cookbook is sweetened with dates, and is made with almond flour and hazelnut butter. It is honestly the perfect amount of sweet while still feeling rich and decadent. And now, I have even more proof that it’s guilt-free!
Okay, that’s it - those were my 5 experiments. I hope they were as eye-opening to you as they were to me.
Now, no doubt some will roll their eyes and view this experiment as unnecessary poking of the bear, but the numbers often paint a frightening picture. 1 in 3 Americans has pre-diabetes, and 88% of Americans have been found to be metabolically unhealthy. Even allowing for a healthy margin of error, these numbers are high. For South Asians this is a harsher reality - a genetic predisposition to metabolic risk factors paired with a high-glycemic diet has sent rates of heart disease and diabetes soaring. We don’t suddenly wake up one day with insulin resistance - it is usually linked to years of lifestyle and diet patterns. Why not stop the cycle earlier, when we have the window of opportunity?!
I think these wearable devices are going to become more and more ubiquitous in coming years, as they provide a powerful stimulus for behavior change and can be used for preventative care. It is empowering to get real data about your body and adapt your practices in response, similar to the way that you might use a Fitbit or an Apple watch. Like most things in life, experimenting this way requires a reasonable level of judgement, but it’s certainly possible to do without obsessing about it or ruining your relationship with food. Hopefully, these devices also get more affordable with time.
In the meanwhile, I hope this post makes the case for you to try incorporating more low-glycemic foods into your rotation this new year. This is even more critical if you’re trying to eat plant-based, as most options involve refined grains and flour. If you want to learn how to make flavorful and satisfying cauliflower rice dishes, protein-rich soups and healthy desserts, check out my cookbook using the links below.
I leave you with a profound thought (but the Internet said it first):
Eating Healthy is Hard. Not Eating Healthy is Hard. CHOOSE your Hard.
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