To measure that effect, there are two quantifiers: glycemic load and glycemic index.
These measurements can help you understand how individual foods influence blood sugar. Glycemic index assigns a score from 0-100 based on how drastically it can make blood sugar rise.
Glycemic load (GL) measures how quickly sugar enters the bloodstream and how much glucose it delivers per serving.
Generally speaking, processed foods and sugary snacks have a high glycemic index (GI). On the other hand, low carbohydrate foods, and those high in fiber or fat, tend to have a low GI.
Glycemic load offers a more real-life view of how food impacts blood sugar. For example, watermelon is a relatively high GI food (80 GI) but has a very glycemic load of only 5.
How well these measurements work is up for debate. Some nutrition experts suggest that they are great tools to help people manage blood sugar and metabolic conditions like diabetes.
The American Diabetes Association, however, suggests looking at the total amount of carbohydrates in food rather than GI or GL.
GI and GL are helpful tools, but they can make things confusing. If you want to keep blood sugar in check, the best way is to ask yourself if your food choices are healthy.
Most vegetables, fruits, whole grains, legumes, nuts, and unprocessed meats are very low GI and GL and have no added sugars. Outside of meats and dairy, they are also rich sources of fiber.
You can use GI and GL if you want to, but you will be able to notice very clear trends emerging: processed foods will quickly spike blood sugar, unprocessed foods will not!