Bread and Coke Smackdown! – A Blood Sugar Experiment

Bread and Coke Smackdown! – A Blood Sugar Experiment

I was shocked to learn just how damaging sugar and high-fructose corn sweetener is on the body. The book Why We Get Fat: And What To Do About It, by Gary Taubes, laid out all the scientific evidence and left a paper (or link) trail that anyone could follow if they want to verify the data for themselves. While the information is still a bit controversial, in spite of the validated research (which is open to individual interpretation), I applied my own critical reasoning and felt I could trust my own judgement. This is partly why I quit eating sugar. Anyone who joins the quitting sugar or low carbohydrate community will become familiar with the health consequences of over-consuming sugar. They also become familiar with the many experts who make certain claims about various foods and why they should be avoided. One such person is Dr. William Davis, author of Wheat Belly, who makes this claim:

“People are usually shocked when I tell them that whole wheat bread increases blood sugar to a higher level than sucrose. Aside from some extra fiber, eating two slices of whole wheat bread is really little different, and often worse, than drinking a can of sugar-sweetened soda or eating a sugary candy bar.”

I’ve come across this claim being referred to on many blogs, podcasts and word-of-mouth. It seems to be widely accepted as true. And [full-disclosure] I like Dr. William Davis and his message, therefore, I accepted his claim when I heard it, even though it seemed a little surprising. Of course, if everybody is saying it, then it must be true, right?

Wanted: Critical Reasoning

News Flash: Just because you believe something, that doesn’t make it true. Even though I like Dr. Davis, and even though I believe he backs up his claim with data that makes sense to me, I still found it bothersome to think that two slices of whole wheat bread are as bad as a 12-ounce can of Coke. So, because I’m curious by nature, I decided to test this claim for myself by having a wheat bread and Coke smackdown. Yeah, baby! There’s nothing like a little critical reasoning in the form of a self-administered experiment. This way, I will see the results for myself, and I’ll use my own body as the test vehicle.

Experiment Number One: Bread, A Love Story

Yes, we all love bread. Right? But I have to be honest and state that when I quit eating sugar, I also quit eating bread and wheat products because of its propensity to convert to sugar. But still, is bread the bad guy here? I quit eating it without really knowing how my body responds when I eat it. And, sure, I miss having bread. But I can handle not eating it. Still, in order to conduct my first experiment, I was going to have to eat two slices of it. But I wasn’t worried about it causing me to go on a sugar binge or start craving sweets until my teeth fell out. I knew I could take one for the team. So my plan was, I would wake up after fasting (during sleep) all night. Before eating, I would check my blood glucose to establish a baseline. Then I would eat two slices of wheat bread for breakfast and begin rechecking my blood sugar ever thirty minutes for the next two hours.

Experiment Number Two: Coke, Unplugged

Just as in the bread experiment, I would wake up and check my blood glucose before drinking the Coke. Next I would drink a 12-ounce can of full-sugar Coke, then begin testing my blood sugar every thirty minutes for the next two hours. My assumption was that even if the bread caused a spike in my blood sugar level, the full-sugar Coke would be worse because it’s basically carbonated sugar water. However, the numbers told a story that surprised me.

(Click for larger view)

Wheat Bread versus Coke – THE RESULTS


SUMMARY: My blood glucose spiked higher on wheat, and the difference between my starting blood glucose level and the peak BG number was also higher after eating bread.


MENU: 2 slices of wheat bread

Fasting Blood Glucose before Breakfast – 86
30 minutes later – 112
60 minutes – 152
90 minutes – 118
120 minutes – 125



MENU: 1 12-oz can of (full sugar) Coke

Fasting Blood Glucose before Breakfast – 97
30 minutes later – 134
60 minutes – 149
90 minutes – 139
120 minutes – 95


What Does It All Mean?

Okay…so what does this mean? First, my results appear to validate Dr. Davis’ claim. Though the actual numbers went higher for the bread (152), it’s important to note that my starting blood glucose level was also lower (86) before eating the bread compared to the level (97) before drinking the Coke. So the actual amount of the spike in my blood glucose (compared to my fasting BG number taken just before eating) was greater after eating the bread. What’s even more interesting is that at the two-hour mark, my blood sugar had returned to normal after drinking the Coke. But after eating the bread, my numbers were starting to climb again at the two-hour mark. Notice how evenly my blood sugar levels climbed and dropped after drinking the Coke. But with the bread, there was a sharp rise between the 30- and 60-minute mark, and a sharp decline between the 60- and 90-minute mark, then the numbers started to rise again at the 2-hour mark. This is crazy, right?

Critical Reasoning, Redux

But let’s take another look here. Bread is a starch, and being a complex carbohydrate, I thought this would mitigate the rise in my blood sugar levels and cause it to happen more slowly. This didn’t happen. It was a rough ride for the bread and a smooth ride for the Coke. So it almost looks like the bread is actually worse than the Coke. But is it? Who, in the real world, would only eat two slices of wheat bread for a meal? Typically, when you have two slices of bread, there’s also going to be some meat, cheese, and maybe a slice of tomato and lettuce in there as well, and perhaps a bit of mayo or mustard. Or you might eat a slice or two with a full meal. Wouldn’t this affect blood sugar levels too? Perhaps eating a sandwich or having bread with a meal isn’t as bad as eating only two slices of bread alone.

Also, consider how often people drink Coke or any sugary soda, for that matter, and how often they don’t eat food while they’re drinking it. Different story here. People sip on sodas during meals as well as in-between meals. Any amount sugar you consume is going to be worse or better depending on what you consume with it. A high-fiber meal that includes protein and vegetables and a can of full-sugar soda wouldn’t be as bad as consuming just the soda alone. It seems to me that the bread versus soda comparison isn’t really a fair one because it’s comparing  bread in a manner that’s not typical. Personally, I have nothing against Coke or sodas in general. When I drink a soda, it’s usually a Coke Zero. But the trouble isn’t the soda companies. There is a demand for their products. And until people become wiser to the dangers of refined sugar and stop buying sodas, Coke (and all soda companies) will, and should, continue to make a product that’s in demand. That’s just capitalism, plain and simple. And I also have nothing against capitalism.


This experiment was certainly an eye-opener. Now I know that the claims being promoted by Dr. William Davis (and others) is true, though it may not accurately reflect the eating habits of most individuals. Your results may vary, but in my opinion, you would be wise to avoid both full-sugar Coke and bread. The damaging affects of sugar (obesity, diabetes, and metabolic syndrome to name a few), is reason enough to quit eating bread and drinking sugary sodas.

Da Capo?

However, this story isn’t over. I think I’m going to have to repeat this experiment with some slight variations. For example, I might eat a sandwich for breakfast and monitor my blood sugar levels and compare it with eating two slices of bread, alone, to see if the numbers improve. Also, what happens if I have a full-sugar Coke with a healthy meal? Would my numbers be any better? To be continued… 


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Author: Scott Milford

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