Take a look at this particular comparison of different fruits and vegetables.
https://phcuk.org/wp-content/uploads/2020/05/Fruits-Vegetables-21.05.2020.jpg#mce_temp_url#

Notice if you eat a boiled potato it is going to have a drastic difference in the amount of glucose in your bloodstream than if you eat cabbage or peas.

Notice if you eat raisons or a banana it will have a much different affect in blood glucose (and amount of insulin the pancreas puts out to control it) than eating an equal amount of strawberry.

Excess carbohydrates, more than the body currently needs for energy, will be converted and stored as fat for later use. For that fat to be used later for energy insulin levels have to be low. Body fat can not be utilized or "burned" in a state of high insulin. How do you keep or cause insulin to be low? Either by not eating at all (that will do it) or by eating only foods that do not raise insulin. Carbohydrates raise insulin. Don't eat carbohydrates (or severely limit them) and insulin goes low allowing the body to tap into its fat reserves and provide the energy needed.

It is pretty simple really. Just not well understood by most people and not promoted by the food or medical industries.