Why a Bagel Can Spike Your Blood Sugar More Than a Doughnut

The breakfast that looks healthy but hits harder

If you asked most people which is worse for blood sugar — a plain bagel or a glazed doughnut — the answer would be obvious. The doughnut is fried, coated in sugar, and sits in a case at gas stations. The bagel is what health-conscious people order at the cafe. It is the responsible choice.

Except it is not. At least not when it comes to glycemic load.

A standard New York-style bagel (about 105 grams) contains roughly 55 grams of carbohydrate. With a glycemic index around 72, that gives it a glycemic load of approximately 25 to 28. That is firmly in the high category.

A glazed doughnut (about 60 grams) contains roughly 22 grams of carbohydrate. Its GI is around 76 — slightly higher than the bagel — but with less than half the carbs, the glycemic load comes out to about 17. That is medium.

The bagel spikes your blood sugar more than the doughnut. And it is not even close.

How is this possible?

Three factors explain the gap:

1. Carbohydrate density. A bagel is essentially a dense ball of refined flour. It is boiled and then baked, which creates that chewy, compact texture. That density packs a lot of starch into a relatively small volume. Gram for gram, a bagel is one of the most carb-dense bread products you can buy.

A doughnut, despite its reputation, is actually lighter. It is fried, which means the cooking process creates air pockets. The glaze adds sugar, but not as much as you might assume — about 6 to 8 grams for a standard coating.

2. Fat slows digestion. A glazed doughnut contains about 14 grams of fat from the frying process. Fat slows gastric emptying, which means the carbohydrates in the doughnut are released into your bloodstream more gradually. The blood sugar rise is slower and lower than it would be if you ate the same carbs without the fat.

A plain bagel has about 1 to 2 grams of fat. There is nothing to slow down the rapid digestion of all that refined starch. It hits your bloodstream fast.

3. Portion size. This is the factor people most often overlook. A standard bagel weighs nearly twice as much as a standard doughnut. If you ate a bagel the size of a doughnut, the comparison would be much closer. But nobody sells bagels that small.

This is not an argument for eating doughnuts

Let me be very clear: this comparison is not suggesting that doughnuts are a health food. A doughnut has more saturated fat, more added sugar per gram, less fibre, and fewer micronutrients than a whole grain alternative. It is nutritionally poor by almost any measure.

The point is different. The point is that the word "healthy" and the concept of glycemic load are not the same thing, and confusing them leads to poor decisions for people managing blood sugar.

A person with type 2 diabetes who chooses a bagel for breakfast because it seems like the healthier option is unknowingly choosing a higher glycemic load than the food they were trying to avoid. The intention is good. The outcome is not.

Carb density: the hidden variable

Glycemic load captures something that glycemic index alone misses: how much carbohydrate you are actually consuming. This is why carb density — the grams of carbohydrate per gram of food — is such a useful concept for diabetes management.

Here is how some common breakfast items compare on carb density:

• Bagel: 0.52 g carbs per gram of food

• White bread: 0.49 g carbs per gram

• Glazed doughnut: 0.37 g carbs per gram

• Croissant: 0.46 g carbs per gram

• Whole wheat bread: 0.43 g carbs per gram

The bagel leads the pack. It is denser in carbohydrate than white bread, which already has a reputation for spiking blood sugar.

What actually makes a better breakfast

If you are managing blood sugar and you want a bread-based breakfast, here are options that perform better on glycemic load:

• Sourdough toast (1 slice): ~15g carbs, GI ~54, GL ~8

• Whole grain English muffin: ~24g carbs, GI ~50, GL ~12

• Rye bread (1 slice): ~15g carbs, GI ~41, GL ~6

All of these have significantly lower GL than the bagel, and they leave room for protein and fat additions (eggs, avocado, nut butter) that further blunt the blood sugar response.

If you genuinely love bagels, a thin bagel or a bagel half with cream cheese will cut the GL roughly in half. The cream cheese adds fat, which slows digestion. It is not perfect, but it is a substantial improvement over a whole plain bagel.

The bigger lesson

The bagel-versus-doughnut comparison is a useful mental model because it highlights a pattern that shows up everywhere in nutrition: foods that look healthy based on ingredients or reputation can have a higher glycemic impact than foods that look unhealthy.

Other examples of this pattern:

• Fruit smoothie vs. chocolate bar: A large mango-banana smoothie can have a GL above 25. A standard chocolate bar is around 12 to 14.

• Granola vs. eggs and toast: A cup of granola with milk can hit GL 20+. Two eggs on sourdough toast lands around 10.

• Orange juice vs. whole orange: A glass of OJ (GL ~15) vs. a medium orange (GL ~5).

In every case, the food perceived as healthier has the higher glycemic load. This does not mean the healthier food is bad — it means that glycemic load is a separate axis from general nutrition, and people managing diabetes need to track both.

Tools like Glyc exist precisely for this reason. You can check the GL of any recipe or meal and see exactly where the carbohydrate load is coming from, rather than relying on assumptions about which foods are "good" and which are "bad."