Blood sugar levels rise after eating foods that contain carbohydrates. This is because carbohydrates are broken down into glucose during digestion, which causes an increase in blood sugar levels. However, some foods affect blood sugar more than others. This article explores what foods increase blood sugar the most.
What is blood sugar?
Blood sugar, also known as blood glucose, is the main source of energy for the cells in our bodies. The levels of glucose in the blood are regulated by two hormones: insulin and glucagon.
Insulin is produced by the pancreas and helps glucose enter the cells, lowering blood sugar levels. Glucagon, also produced by the pancreas, signals the liver to release stored glucose into the bloodstream when levels are low, raising blood sugar.
After eating a meal, the carbohydrates are broken down into glucose and enter the bloodstream, causing a rise in blood sugar. The pancreas responds by releasing insulin to transport the glucose into the cells for use as energy.
In people without diabetes, blood sugar levels typically range between 70-100 mg/dL when fasting and less than 140 mg/dL two hours after eating. In people with diabetes, these levels may be higher.
How do foods affect blood sugar?
The main nutrient that influences blood sugar levels is carbohydrates. Carbohydrates are found in sugars, starches, and fiber.
Simple carbohydrates have a simple chemical structure and include sugars like glucose, fructose, sucrose, and lactose. They can be naturally found in foods like fruits, dairy products, and honey.
Complex carbohydrates, also known as starches, have a more complex chemical structure. Foods like bread, potatoes, pasta, rice, and grains contain starches.
Fiber is also a complex carbohydrate but does not get fully broken down and absorbed. Therefore, it has less of an impact on blood sugar.
Protein and fat do not directly impact blood sugar levels but can help slow digestion and the absorption of carbohydrates, resulting in a more gradual rise in blood sugar.
Foods that increase blood sugar the most
The foods that increase blood sugar the most are high glycemic index foods. The glycemic index is a scale that ranks carbohydrate-containing foods based on their effect on blood sugar levels.
High glycemic foods cause a rapid increase in blood sugar because they are quickly broken down into glucose. Low glycemic foods cause a slower, more gradual rise in blood sugar.
Here are some high glycemic foods that can significantly increase blood sugar levels:
Sugary foods and beverages
- Soda, fruit juice, sports drinks, and sweet tea
- Candy, ice cream, cookies, cakes, and desserts
- Jams, jelly, honey, and syrup
- Dried fruits and fruit smoothies
Refined grains
- White bread, crackers, pretzels, and baked goods made with white flour
- White rice, couscous, and instant oatmeal
- Breakfast cereals like corn flakes, puffed rice, and bran flakes
Starchy vegetables
- Potatoes and french fries
- Corn
- Parsnips, winter squash, and pumpkin
Foods made with refined grains and flours, like white bread, raise blood sugar rapidly because the outer bran and germ have been removed during processing. This leaves only the starchy endosperm, which is quickly broken down into sugar.
Starchy vegetables like potatoes consist almost entirely of carbohydrates, causing a sharp spike in blood glucose.
Foods that have a moderate effect on blood sugar
Some carbohydrate-containing foods have a more moderate effect on blood sugar levels. While they can still raise blood sugar, they do not spike it as dramatically as high glycemic foods.
Here are some examples of medium glycemic foods:
- Sweet potatoes, yams, butternut squash
- Bananas, grapes, apricots, plums
- Barley, bulgur, couscous
- Beans, lentils, chickpeas
- Sweet corn
- Carrots, beets
The fiber, fat, and protein content in these foods helps slow the digestion and absorption of carbohydrates. This leads to a more gradual rise in blood sugar compared to high glycemic foods.
Foods that minimally impact blood sugar
Some foods have very little effect on blood sugar levels. Non-starchy vegetables, nuts, seeds, avocados, and oils contain very few digestible carbohydrates per serving:
- Broccoli, spinach, kale, cabbage, lettuce, cucumbers
- Cauliflower, zucchini, asparagus, peppers, mushrooms
- Nuts like almonds, walnuts, cashews, and peanuts
- Nut butters
- Seeds like pumpkin, sunflower, chia, and flaxseeds
- Avocados
- Oils like olive oil, coconut oil, flaxseed oil
- Cheese
- Greek yogurt
Protein foods like meat, poultry, fish, and eggs have no carbohydrates so they do not directly raise blood sugar. However, protein helps slow digestion which can minimize blood sugar spikes when eaten with carbohydrates.
How to minimize blood sugar spikes
Here are some tips to help prevent sharp rises in blood sugar when eating:
- Choose whole, minimally processed grains like quinoa, brown rice, whole wheat or rye bread
- Eat plenty of non-starchy vegetables
- Include protein, fat, and fiber at meals
- Avoid sugary beverages and limit sweets or desserts
- Spread carbohydrate intake evenly throughout the day
- Pair high glycemic foods with lower glycemic options like vegetables or lean protein
- Exercise regularly to increase insulin sensitivity
People with diabetes may also need to coordinate their medication with meals and monitor blood sugar levels closely when eating high carb foods.
The glycemic index of common foods
The glycemic index ranks foods on a scale of 0–100 based on their effect on blood sugar levels. The numbers represent a comparison to the glycemic response of pure glucose, which has a GI value of 100:
- Low GI: 55 or less
- Medium GI: 56–69
- High GI: 70 or more
Here is the glycemic index for some common foods:
| Food | Glycemic Index |
|---|---|
| Glucose (reference food) | 100 |
| White bread | 75 |
| Watermelon | 72 |
| Rice cakes | 82 |
| Corn flakes | 84 |
| Instant oatmeal | 83 |
| Russet potato, baked | 111 |
| Pretzels | 83 |
| Soda | 68 |
| Banana | 51 |
| Sweet potato | 70 |
| Grapes | 59 |
| Apple | 38 |
| Orange | 42 |
| Milk | 27 |
| Yogurt | 14 |
| Peanuts | 14 |
As shown in the table, foods like white bread, rice cakes, corn flakes, potatoes, and pretzels are high glycemic foods with values of 70 or above. Foods like non-starchy fruits and vegetables, dairy foods, and nuts are lower glycemic foods.
Tips for managing blood sugar with diet
Here are some additional tips for controlling blood sugar levels through diet:
Eat more low glycemic foods
Choosing low glycemic foods like non-starchy vegetables, fruits, minimally processed grains, beans, lentils, nuts, seeds, and dairy can help maintain steady blood sugar levels.
Combine carbs with protein, fat, and fiber
Pairing carbohydrates with protein, fat, and fiber slows digestion and prevents blood sugar spikes. For example, having vegetables and chicken with rice rather than just plain rice.
Avoid large portions of carbs
Spreading carbohydrate intake throughout the day helps prevent large spikes from big carb-heavy meals. Limiting portion sizes of grains, starches, and sugars can also minimize their effect.
Stay hydrated
Drinking water helps regulate blood sugar levels by preventing dehydration.Aim for 6-8 glasses of fluid daily.
Manage stress
High stress causes the body to release hormones that increase blood sugar. Managing stress through relaxation techniques, adequate sleep, and exercise helps stabilize levels.
Increase fiber intake
Soluble fiber from foods like vegetables, fruits, beans, oats, and nuts helps slow digestion and sugar absorption. Aim for 25-35 grams of fiber daily.
Read labels
Check the total carbohydrate and fiber content on nutrition labels to identify high sugar, low fiber foods that can spike blood sugar. Limit added sugars.
Get regular exercise
Exercise helps your body use insulin more efficiently and lowers blood sugar in the long-term. Aim for 30-60 minutes daily to keep levels in check.
Foods to eat in moderation or avoid
Here are some foods that are best consumed in moderation or limited on a blood sugar friendly diet:
Sugary foods and beverages
Soda, juice, candy, ice cream, pastries, cakes, cookies and other sweets can cause blood sugar spikes. Limit portion sizes and frequency.
White flour products
Foods made with white, refined flour like bread, crackers, pretzels, and baked goods digest quickly into glucose. Opt for 100% whole grain options.
Starchy vegetables
Potatoes, corn, winter squash, and parsnips are high glycemic. Limit portion sizes and pair with proteins or healthy fats.
Dried fruit
Dates, raisins, cranberries, cherries, and other dried fruit are condensed sources of fruit sugar. Enjoy in small portions as a treat.
Fruit juice and smoothies
Juice contains fruit sugar without the beneficial fiber of whole fruit that slows absorption. Limit to half a cup daily.
Refined grains
Refined and processed grains like white rice, couscous, grits, and instant oatmeal digest quickly. Opt for whole grains like brown rice, quinoa, and oats.
Conclusion
Foods that increase blood sugar the most are those high on the glycemic index scale. Examples include sugary foods and beverages, refined grains, starchy vegetables, potatoes, and dried fruit. To help maintain steady blood sugar levels, choose non-starchy vegetables, proteins, healthy fats, high fiber grains, beans, lentils, nuts, seeds, and minimally processed dairy foods. Limit portion sizes of carbohydrate-dense foods and spread intake throughout the day. With proper diet and lifestyle management, blood sugar levels can be well controlled.
