While white bread’s occasional spike in your blood sugar is probably harmless, your body can become less responsive to insulin to bring down your blood sugar. Over time, consistently high levels of glucose in your bloodstream can lead to type 2 diabetes (per Houston Methodist). People with type 2 diabetes need to be particularly careful not to eat foods like white bread before their meals, according to a 2015 pilot study in Diabetes Care. The small study found that people with metformin-treated type 2 diabetes who ate ciabatta bread and orange juice before their main meal had higher post-meal glucose levels than when they had the bread and juice after their meal.
According to Houston Methodist, consuming too many carbohydrates at a time could also lead to weight gain. When your cells have enough glucose for energy, your liver stores the excess glucose for later use. If you already have enough stored glucose in your liver, your body will convert this leftover glucose into fat.