If you're overweight around the middle and eat a meal full of carbs, your blood sugar and insulin spike more than if you ate a meal with lots of butter or olive oil—but your body doesn’t make as much insulin for how much sugar is in your blood.

If you swap out a small amount of fatty foods for sugary or starchy ones for six weeks, your body releases less insulin after eating—even though your blood sugar goes up the same—which might mean your pancreas isn’t working as well.

People with obesity tend to have higher insulin levels when fasting and their blood sugar spikes more after eating carbs, but their bodies still use the sugar from those carbs just like lean people do.

When healthy people eat a carb-rich meal, their muscles get more blood flow and their blood vessels relax, even though their body also sends signals to tighten blood vessels—this might help their body absorb sugar from the meal better.

Reduction in dietary carbohydrate intake improves postprandial glycemic control and reduces fasting and postprandial serum triglyceride concentrations in humans.