Bread is a staple food for billions of people worldwide — but not all bread is equal when it comes to blood sugar. White bread sits near the very top of the glycemic index chart, and understanding why can transform the way you think about your daily carbohydrate choices.

What Is the Glycemic Index of White Bread?

White bread has a glycemic index of approximately 70–75, which places it firmly in the high GI category (70 and above). Some commercial white breads, particularly highly processed varieties, can score even higher — up to 85 or more.

In fact, white bread is so rapidly digested that it is often used as the reference food in GI testing, alongside pure glucose, both of which are assigned a GI of 100 in some older testing frameworks.

Bread Type	Glycemic Index	GI Category
White bread (processed)	70–85	High
Whole wheat bread	65–74	Medium–High
Sourdough bread (wheat)	48–54	Low–Medium
Rye bread (100% rye)	41–56	Low–Medium
Pumpernickel bread	41–46	Low
Barley bread	34–42	Low
Ezekiel bread (sprouted)	36–42	Low

Why Does White Bread Have Such a High GI?

White bread is made from highly refined wheat flour, which has had the bran and germ removed during milling. This processing strips away fiber, protein, and fat — leaving behind primarily starch made of rapidly-digested amylopectin chains.

Several factors contribute to white bread’s high GI:

• Very fine particle size — the flour is so finely milled that the starch granules are easily accessible to digestive enzymes, speeding up conversion to glucose
• Minimal fiber — fiber slows starch digestion; white bread contains very little
• Low protein and fat content — both nutrients slow gastric emptying and glucose absorption
• High amylopectin content — this branched starch structure is digested more rapidly than amylose (found in more intact grains)
• Porous structure from yeast leavening — commercial bread-making creates a light, airy structure with large surface area that digestive enzymes can quickly access

Glycemic Load of White Bread

Two slices of white bread (about 60g) contain approximately 26–28g of carbohydrates. With a GI of 75:

GL = (75 × 27) ÷ 100 = 20

A glycemic load of 20 is considered high. Two slices of white bread have about the same blood sugar impact as a can of regular soda. This is why white bread is frequently cited as one of the most problematic foods for blood sugar management.

White Bread vs. Whole Wheat Bread: Is Whole Wheat Actually Better?

This is one of the most common misconceptions in nutrition. Many people switch from white bread to “whole wheat” bread believing they are making a significant improvement — but standard supermarket whole wheat bread often has a GI only marginally lower than white bread.

Bread Type	GI	Carbs (2 slices)	Glycemic Load
White bread	75	~27g	~20
Whole wheat bread	70	~24g	~17
Sourdough wheat	52	~25g	~13
100% rye bread	50	~22g	~11
Ezekiel bread	36	~24g	~8.6

Why doesn’t whole wheat bread score much better? Because most commercial “whole wheat” breads are still made from finely milled flour — just with some bran added back. The key is the particle size and degree of processing, not just the presence of whole wheat on the label. Look for bread made with whole grain kernels or stone-ground flour for significantly lower GI.

What White Bread Does to Blood Sugar

After eating two slices of white bread, blood glucose typically rises sharply within 30–45 minutes, peaks, and then drops — often triggering a hunger response even when calorie intake was adequate. This blood sugar roller coaster is associated with:

• Increased hunger and cravings within 1–2 hours
• Energy dips and fatigue
• Increased insulin secretion, which promotes fat storage
• Over time, contributes to insulin resistance with regular overconsumption

Best Low-GI Bread Alternatives to White Bread

1. Sourdough Bread (GI: 48–54)

Sourdough fermentation produces lactic acid, which lowers the bread’s pH and slows starch digestion. This is why genuine sourdough — made with a live culture and long fermentation — has a notably lower GI than standard bread, including whole wheat. Look for sourdough with simple ingredients: flour, water, salt, and starter.

2. 100% Rye Bread (GI: 41–56)

Dense rye bread made with whole rye flour has a substantially lower GI than wheat bread. Rye contains beta-glucan and other fibers that significantly slow glucose absorption. Note: light rye bread made with refined rye flour scores much higher.

3. Pumpernickel Bread (GI: 41–46)

Traditional German pumpernickel is made with whole rye kernels, steam-baked for extended periods. The intact grain structure and dense composition result in one of the lowest GI values among common breads.

4. Ezekiel / Sprouted Grain Bread (GI: 36–42)

Made from sprouted whole grains and legumes, Ezekiel bread has a very low GI. Sprouting activates enzymes that break down antinutrients and change the starch structure, reducing glycemic impact. It also provides more protein and fiber than conventional bread.

5. Barley Bread (GI: 34–42)

Bread made with whole grain barley flour has among the lowest GI values of any bread, thanks to barley’s exceptionally high beta-glucan content. Beta-glucan forms a viscous gel in the gut that dramatically slows sugar absorption.

Tips for Reducing White Bread’s Glycemic Impact

If you’re not ready to give up white bread entirely, these strategies can help reduce its blood sugar impact:

1. Toast the bread — toasting lowers GI slightly by changing the starch structure
2. Refrigerate and reheat — cooling bread creates resistant starch; reheating retains some of this effect
3. Add protein-rich toppings — eggs, nut butter, tuna, or cottage cheese slow digestion and flatten the blood sugar curve
4. Add fat — avocado, olive oil drizzle, or cheese slows gastric emptying
5. Use vinegar — a drizzle of balsamic or apple cider vinegar has been shown to reduce post-meal blood sugar by 20–30%
6. Eat bread at the end of a meal, not the beginning — eating carbohydrates last has been shown to significantly reduce post-meal glucose spikes

Frequently Asked Questions

Is white bread worse than sugar for blood sugar?

White bread (GI 75) actually has a higher GI than table sugar (sucrose, GI ~60–65). However, the glycemic load depends on the portion — a small amount of sugar may have less blood sugar impact than two slices of bread due to the larger carbohydrate volume in bread.

Does toasting white bread lower its GI?

Yes, modestly. Toasting partially converts some starches to resistant starch and denatures proteins, lowering GI by roughly 10–15 points. Allowing toast to cool further increases this effect. However, toasted white bread remains in the medium-to-high GI range.

Can people with diabetes eat white bread?

Occasionally and in small portions, yes. But white bread is generally not recommended as a dietary staple for people with diabetes due to its high GI and glycemic load. Switching to sourdough, rye, or sprouted grain bread is a more sustainable improvement.

Conclusion: White Bread Is One of the Highest-GI Staple Foods

White bread’s glycemic index of 70–85 places it among the most rapidly digested carbohydrate sources in the modern diet. Its high glycemic load, low fiber content, and minimal nutritional value beyond calories make it a suboptimal choice for anyone concerned with blood sugar, energy levels, or long-term metabolic health.

The good news: there are excellent low-GI bread alternatives that are just as satisfying. Sourdough, 100% rye bread, pumpernickel, and sprouted grain breads can scratch the same itch with far less blood sugar impact. If you only make one dietary change for better blood sugar control, switching from white bread to sourdough or whole rye is one of the most impactful moves you can make.