One milk chocolate bar has 26 grams of carbohydrates and 1 ounce of dark chocolate has 17 grams, most of which is from sugars or refined carbohydrates. Refined carbohydrates can cause spikes in your blood sugar, which can make your body resistant to insulin over time and may lead to Type 2 diabetes. The excess sugar may also send you to the dentist more often than you’d like with tooth decay and cavities.