Gas is a presence of air in your digestive tract, sometimes caused by the breakdown of certain foods, and bloating can be a symptom of gas. Because there's air in your system, it can feel as though your abdomen is swollen and heavy. Chocolate is processed from cacao beans and mixed with sugar and an emulsifier to make a tasty treat, and none of these ingredients is known to cause gas or bloating. However, when milk or high fructose corn syrup are added to the mix, these can cause gas in some people.
Lactose is a sugar that occurs naturally in milk. Many chocolate bars contain milk in some form -- for example, a Snickers bar contains skim milk, lactose and milk fat. If you're lactose intolerant, you have difficulty digesting lactose and may experience gas, bloating or even diarrhea from eating chocolate that contains milk ingredients.
If eating milk chocolate gives you gas, try dark chocolate, which typically doesn't have any milk added to it. Check the ingredients list to be sure. Also, look through the ingredients for high fructose corn syrup, a sweet syrup processed from corn that may lead to gas. Some sugar-free chocolate is sweetened with sugar alcohols, such as sorbitol, which causes gas in some people. Instead, find a dark chocolate made with organic sugar or evaporated cane juice.