Freezing bananas before blending them into smoothies has become a popular tip in health circles, with some claiming it can increase resistant starch and help reduce blood sugar spikes. The science, however, is more nuanced. Bananas naturally change their carbohydrate composition as they ripen, with resistant starch declining and sugars increasing over time. While cooling cooked foods like rice or potatoes can create additional resistant starch through a process called retrogradation, bananas are typically frozen raw — meaning the same mechanism may not apply. Current research suggests that factors such as banana ripeness, smoothie ingredients, and individual metabolic differences likely play a much larger role in post-meal glucose response than freezing alone.