At first glance, it may seem like all foods can be split up into three categories: foods that help keep blood sugar stable (good), foods that spike your blood sugar (bad), and foods that fall somewhere in between (sometimes good, sometimes bad). While this simplified approach can be helpful for folks with diabetes or those who need to watch their blood sugar, it does also leave out some important factors in how digestion works and how we get energy from food.
For starters, “it’s completely normal for blood sugars to rise after eating, that’s what the body is designed to do,” says Amna Haq, M.S., R.D., L.D.N., a registered dietitian and owner of the Inclusive Dietitian in Chicago. “When you eat carbohydrates, they’re broken down into glucose, which enters the bloodstream and provides energy for your cells. In response, your pancreas releases insulin, a hormone that helps move that glucose from your blood into your cells to be used for energy.”
Meet the experts: Amna Haq, M.S., R.D., L.D.N., a registered dietitian and owner of the Inclusive Dietitian in Chicago; Juliana Vocca, M.S., R.D., a registered dietitian and owner of Prime Women Nutrition in Moorestown, NJ.
Still, even though your body needs the glucose coming in from your food, sometimes it comes in too fast, resulting in a blood sugar spike. “When a food ‘spikes’ your blood sugar, it means glucose is entering your bloodstream faster than your body can comfortably manage,” explains Juliana Vocca, M.S., R.D., a registered dietitian and owner of Prime Women Nutrition in Moorestown, NJ. “A spike isn’t about how much carbohydrate you ate; it’s about how quickly that carbohydrate is digested and absorbed.”
Here, dietitians explain why it’s important to limit foods that spike your blood sugar, plus the big ones to watch out for.
Are blood sugar spikes always bad?
Technically, blood sugar spikes are not always harmful. But spikes that occur too frequently can start to cause problems for your health. “Occasional spikes are normal. But frequent, rapid spikes can make your cells less responsive to insulin, which is one of the early steps toward insulin resistance and type 2 diabetes,” Vocca explains. She adds that if glucose enters the bloodstream too quickly, the pancreas can produce more insulin than the body needs. “If insulin overshoots a bit, which is common after a big spike, blood sugar can drop quickly,” says Vocca. “That rapid dip is what causes the ‘crash,’ leading to fatigue, shakiness, irritability, and sudden hunger.”
If you are experiencing frequent and uncontrolled blood sugar spikes and have started to develop insulin resistance, it can even start to affect other systems in your body. According to research in the journal PLOS One, repeated glucose spikes and insulin resistance can damage the health of your blood vessels, potentially increasing your risk of heart disease.
Even so, blood sugar spikes can be a good thing under the right conditions. “Following a hard workout, your muscles are primed to take up glucose to quickly replenish glycogen stores. A faster rise in blood sugar can actually be helpful here, especially if paired with protein,” says Vocca. Likewise, if you have type 1 diabetes and your blood sugar drops too low, a rapid spike is needed to bring your levels back up to normal. “Athletes sometimes rely on quick‑absorbing carbs (like gels and sports drinks) to maintain energy during long races,” Vocca adds. “In these situations, a spike is functional rather than harmful.”
Foods to limit that spike your blood sugar
“The goal isn’t to prevent blood sugar from rising altogether, it’s to encourage a steadier, more gradual response,” says Haq. Pairing higher-carbohydrate foods with protein and healthy fats can help slow down the increase, as can limiting your intake of foods that send glucose flying into your bloodstream. Here are the foods that dietitians say you should limit or avoid.
Sugar-sweetened drinks
Sugar-sweetened sips like soda, energy drinks, and sweetened teas are some of the biggest culprits when it comes to blood sugar spikes. “These contain carbohydrates but little to no fiber, protein, or fat to slow digestion,” Haq explains.
Refined grains
The grains in white bread, white rice, pasta, and crackers have been stripped of the bran and the germ, where the fiber and nutrients reside, leaving only the starchy endosperm. The result: “These are digested more quickly than their whole-grain counterparts, leading to a faster rise in blood sugar levels,” says Haq.
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Pastries and baked goods
“Muffins, croissants, cookies, and donuts are foods that combine refined flour and added sugar, a double hit that digests quickly and raises blood sugar sharply,” explains Vocca. “Many also contain fats that don’t slow digestion enough to offset the rapid carb absorption.”
Processed salty snacks
While you may not think about them as often as the sweet treats above, Haq says salty snacks like crackers, pretzels, and chips can also spike your blood sugar. “They are still made with refined starches and provide little fiber or protein to slow down absorption of the glucose,” she notes.
Fruit juice
Fruit juices that don’t contain any added sugar may seem like healthy picks, but their natural sugars can rapidly increase your glucose levels without the addition of the fiber present in the whole fruit. “In fact, juice is often used to treat low blood sugar because it raises blood glucose quickly,” Haq adds.
Some breakfast cereals
While there are some high-fiber cereals that can be part of a healthy breakfast, the low-fiber, high-sugar varieties can cause blood sugar spikes. “They are made from processed grains that have been puffed, flaked, or extruded, processes that make them digest even faster,” Vocca says. “Add sugar on top, and you get a rapid rise in blood glucose early in the day.”
Hot potatoes
“Potatoes are rich in rapidly digestible starch. When they’re mashed or fried, the physical structure breaks down, making the starch even easier to convert to glucose,” explains Vocca. “Without fiber or protein alongside, they can cause a swift rise.” That said, if you cool the potatoes first, it’s a different story. Cooling potatoes after cooking turns the starch into resistant starch, which acts like fiber and serves as food for the good bacteria living in your gut. Research shows that resistant starch may even improve insulin sensitivity, helping your body better respond to blood sugar spikes in the future.
The bottom line
If you’re working hard to keep your blood sugar levels stable, limiting your intake of these foods—and especially avoiding eating them by themselves—is a smart first step. Still, you don’t need to cut these foods out entirely if you are trying to limit blood sugar spikes. “I don’t believe there is one single food that someone with high blood sugar levels must completely avoid. Blood sugar management is about the overall pattern of eating,” says Haq. “A person can still enjoy their favorite foods by considering portions, pairing carbohydrates with protein and fiber, and building balanced meals that support steady energy and satisfaction.”
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