9 Worst Foods Causing High Blood Sugar – High blood sugar can lead to a multitude of unhealthy side effects, such as weakness, confusion, fatigue, abdominal pain, and blurred vision. Over time, consistently high blood sugar may even lead to diabetes, which is what an estimated 34.2 million people have in the United States. Simply speaking, having high blood sugar—also referred to as high blood glucose—means there is too much sugar in your blood. This is either because your body has too little insulin or your body isn’t functioning with insulin properly. Although this may feel uncontrollable at times, there are ways to manage your blood glucose levels. In fact, avoiding some of the worst foods for your blood sugar is a great place to start.
What makes an item of food good or bad for your blood glucose? According to the Mayo Clinic, a blood-sugar-friendly diet is one that consists of plenty of nutrient-dense foods such as high-fiber foods, healthy non-processed carbohydrates, fish, and healthy fats like unsaturated or polyunsaturated. As far as foods to avoid, these include things that are heavy in added sugar and refined carbs, with very little protein or fiber to back it up.
We’ve compiled a list of the worst foods you could eat if you have high blood sugar, according to research and expert dietitians.
Some people may try to avoid white or brown sugar if they’re watching their blood glucose levels, which may in turn cause them to reach for something more natural like honey or agave syrup. Unfortunately, even though these sources of sugar are more natural than refined white sugar, they can still cause spikes in your blood sugar.
For example, if you’re looking at the glycemic index—which is used to determine how quickly a certain food can increase your blood sugar, with 100 being the fastest and 1 being the slowest—table sugar ranks at 65 and honey is just underneath it at 61. In a study published by the Journal of Nutrition, prediabetic participants who consumed either honey or white sugar saw very similar increases in their blood sugar and inflammatory markers.
What this means is that natural sweeteners can still spike your blood glucose just as much as white sugar. So instead of reaching for honey or agave, try a zero-calorie sweetener like monk fruit or stevia.
Eating deep-fried foods can wreak havoc on your blood glucose levels. This type of food is often loaded with trans fat because of the oil used to fry it. According to Foods, trans fats can contribute to insulin resistance, something that can lead to an excess of sugar in the blood.
The Cleveland Clinic also says that fried food can increase your risk of high cholesterol, weight gain, and development of type 2 diabetes, and one study published in the American Journal of Clinical Nutrition even found that an increased consumption of fried food led to an increased risk of diabetes.
Also, if you think about the type of food that is being fried, where it sits on the glycemic index can play a role as well. For instance, French fries are just deep-fried white potatoes, and these type of potatoes already have a high glycemic count. That plus the fact that they’re fried in trans fats makes this one of the worst foods for blood sugar.
White potatoes may not be the best food for your blood sugar. You don’t have to completely avoid this starch altogether, but pairing it with some fiber or protein can help limit its effects on your glucose levels.
While this food is considered to have a high glycemic index, and therefore can spike your blood sugar faster than foods with a lower glycemic index, researchers say that it also depends on how they’re prepared. According to Nutrients, potatoes that are prepared mashed or fried are going to have a greater impact on your blood sugar than those that are baked or boiled. The variety of potato also plays a role, with boiled carisma potatoes having a much lower impact than boiled desiree or charlotte potatoes.
If you’re watching your blood sugar levels, you may want to severely limit your consumption of trans fats because according to the Scandinavian Journal of Food and Nutrition, trans fats can increase a person’s insulin resistance if they have type 2 diabetes. This can directly impact your blood sugar levels because insulin is one of the most important hormones in regulating your blood glucose levels.
Unfortunately, limiting your trans fats can be difficult due to the sheer number of delicious foods that contain it, such as many processed baked goods, frozen dinners, microwave popcorn, shortening, fried food, and some non-dairy coffee creamers.
“Many fruit-flavored yogurts are packed with more sugar than some desserts,” says Sarah Anzlovar, RD, a registered dietitian and owner of Sarah Gold Nutrition. “Instead, try plain Greek or Icelandic yogurt and add a little honey to sweeten it yourself.”
Both Greek yogurt and Icelandic yogurt have more protein than regular yogurt, which can help balance your blood sugar. To dress up your yogurt, top it with fresh fruit or seeds for some added fiber. Anzolvar says that the fiber may help to stabilize blood sugar as well. This is because even though it is a type of carbohydrate, your body doesn’t break it down, and therefore it can’t cause a spike in blood sugar levels.
Smoothie bowls are just bowls of, you guessed it, smoothies, that just come with a little more decor on top—such as fruit, nuts, or granola. The most common smoothie bowl is the acai bowl, made of deep purple fruit. Although delicious, and typically nutritious, premade ones don’t have the same effect as a fresh bowl.
“Nothing against fruit or smoothies, but when you buy a pre-made smoothie, your smoothie most likely will be made mostly from fruit juices such as a blend of apple juice and pineapple juice mixed together and it lacks any form of dietary fiber and protein,” says Roxana Ehsani, MS, RD, CSSD, LDN, and national media spokesperson for the Academy of Nutrition and Dietetics.
Ehsani continues to say that both dietary fiber and protein are rare to find in pre-made smoothies and smoothie bowls. A lot of those pre-made bowls found in the grocery stores are high in total carbohydrates, which will increase your already high blood sugar even more. Instead, she believes it’s best to make your smoothies and smoothie bowls at home. Or, ask your local smoothie shop to add some real fruit—both fresh and frozen work.
“Limit the fruit juice,” says Ehsani. “Instead, use milk or non-dairy milk, or even kefir, and add a source of fiber such as fresh or frozen fruit. Plus, some seeds or nuts like chia seeds or flax seeds.” She says you can even add a scoop of peanut butter, protein powder, or Greek yogurt to keep your blood sugar more stable with extra protein added as well.
According to Melissa Azzaro, RDN, LD, a registered dietitian and podcast host at Hormonally Yours, foods high on the glycemic index raise blood sugar faster than foods that are lower on the glycemic index. This includes white bread, white rice, potatoes, soda, and snacks like potato chips and pretzels.
However, you don’t need to rule them out completely. “The glycemic index only measures foods when eaten alone,” says Azzaro. “So, to lower their impact on blood sugar, don’t eat them alone and instead pair them with foods high in protein and fiber.”
“You might be overwhelmed by all the choices in the grocery aisles, especially when it comes to the cereal aisles,” says Ehlani. “Some cereals may be really high in total carbohydrates and lack both dietary fiber and protein, two nutrients that will keep your blood sugar stable and in control.”
If you’re unsure of which cereals to choose from, Ehlani suggests that it’s best to opt for a cereal that has at least three grams of dietary fiber per serving and at least three grams of protein per serving. However, if you end up with a cereal that isn’t top-grade, don’t panic, because there are ways to balance it out.
“You could even add some protein on the side if you do choose a higher carb cereal,” says Ehlani. “Try serving it with a side of scrambled eggs or sprinkle some chopped-up walnuts into your bowl. Or, have a side of Greek yogurt or cottage cheese.”
You won’t feel as happy as a kid in a candy store when you hear about this one because sweet treats are on the “do not eat” list.
“Unfortunately, if your blood sugar is already high, the last thing you should be eating is handfuls of candy, which will continue to make it go sky high,” says Ehlani. “No matter what type of candy you are choosing it likely won’t help your blood sugar numbers. It is best to be avoided until your blood sugar is in a safer range.”
A previous version of this story was published on August 12, 2022. It has been updated to include additional copy and proofreading revisions, additional research, and updated contextual links.