What are the side effects of eating too many carbs?

Answer 1

A diet too high in carbohydrates can upset the delicate balance of your body's blood sugar level, resulting in fluctuations in energy and mood that leave you feeling irritated and tired. In addition, too much carbohydrate can lead to weight gain, obesity, Diabetes and potentially other diet related diseases.

Answer 2

Adverse affect is a raise in blood insulin levels.
Insulin will in turn stimulate the liver to convert the large amount of carbohydrates to lipids. These lipids are then stored in lipocytes (fat-cells).
In short: you get fat.

Long term adverse effects include type 2 diabetes, or frank insulin resistance.

Answer 3

I'm not sure it's a "side" effect, rather the direct effect -- a person will become fat, which may lead to type 2 diabetes