Why are carbohydrates unhealthy?

One of the worst types of carbs to eat while on a diet is pasta. Pasta should truly only be eaten if you plan on burning a lot of energy in a short amount of time. For example, if you had pasta the night before a big race, or before a game or sport in which you need a lot of energy quickly, pasta would be a good choice. A bad thing is that pasta strictly has no nutritional value other than carb and sugar which help produce energy (it may also have some grain depending on the flour used to create the pasta). However, if you have too much energy that you don't burn, the energy will turn into extra fat.