Most people try to make healthier choices as they work on improving their blood sugar. I hear it every week in clinic:
“Doc, I stopped eating donuts. I switched to a ‘healthy’ breakfast cereal. Why isn’t my blood sugar any better?”
It feels unfair — and honestly, it is. Many breakfast foods marketed as “heart healthy,” “whole grain,” or “balanced” can create massive glucose spikes, sometimes worse than a donut.
In a recent video on my YouTube channel, I break down exactly why this happens and what you can do about it.
👉 Watch the full explanation here: https://www.youtube.com/watch?v=45-0oj_lwhU&t=1s
Let’s dive deeper into what your CGM is actually showing you — and why your morning cereal may be sabotaging your progress.
The Surprising Truth: Donuts Aren’t Always the “Bad Guy”
Believe it or not, per ounce, a donut contains less sugar than ketchup.
That doesn’t make donuts a health food — but it does illustrate how easy it is to misjudge what truly impacts your blood sugar.
Many cereals are extremely high in carbohydrates with very little fat, which means they digest fast. Too fast. That rapid digestion causes the bloodstream to get flooded with glucose all at once, leading to the steep spike you might be seeing on your Dexcom or Libre.
Let’s Look at the Numbers: Raisin Bran as an Example
Raisin Bran is often marketed as “heart healthy.” But here’s what one 1-cup serving contains:
- 190 calories
- 47 grams of carbohydrates (equal to ~3 slices of bread!)
- 7 grams of fiber
- 5 grams of protein
- 1 gram of fat
At first glance, it sounds balanced. But the low fat and protein are the key reasons everything hits hard and fast.
Your body simply digests pure carbohydrates much faster than meals containing a combination of macros.
So Why Does a Donut Sometimes Look Better on a CGM?
A donut contains carbs, but it also contains fat — and fat is a powerful regulator of digestion.
Fat slows gastric emptying, meaning carbohydrates enter your bloodstream more gradually. That slower absorption can translate to a lower spike, even if the food isn’t “healthy.”
Again — I am not recommending donuts for breakfast!
But I am recommending that you:
✔ understand your macronutrient balance
✔ rethink “healthy” marketing claims
✔ combine foods that keep your glucose stable
What a Balanced Breakfast Actually Looks Like
A glucose-friendly breakfast should include all four macronutrient components:
✔ Fiber
Slows absorption and feeds gut health.
✔ Carbohydrates
Yes, you can (and should!) have carbs — just not by themselves.
✔ Protein
Supports stable energy and reduces cravings.
✔ Fat
The secret weapon for flatter CGM lines.
This combination helps prevent sharp spikes and crashes, keeping your energy steady through the morning.
Try This CGM Experiment Yourself
If you wear a CGM like Dexcom or Libre, here’s a simple, eye-opening test:
- Eat one cup of cereal by itself and watch what your CGM does.
- On another day, eat a balanced breakfast with carbs + protein + fat.
- Compare your glucose curves.
Most patients are shocked by the difference.
Share your findings with me in the comments on YouTube — I love seeing what you discover.
👉 Watch the full video here: https://www.youtube.com/watch?v=45-0oj_lwhU&t=1s
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