Why do cardiologists frequently group highly refined carbohydrates such as white bread with sugary items in terms of metabolic stress?

They are quickly broken down into glucose, leading to rapid blood sugar spikes.

Highly refined carbohydrates—including white bread, white pasta, and white rice—are problematic because their processing strips away the bran and germ, removing beneficial fiber and nutrients. This leaves behind largely starch, which the body rapidly converts into glucose during digestion. This swift conversion causes significant and frequent rapid blood sugar spikes. Chronic exposure to these sharp increases in blood glucose places ongoing stress on the metabolic system, which contributes to increased systemic inflammation and raises overall cardiovascular risk over the long term, mirroring the negative effects associated with high added sugar intake.