Is less than 20 carbohydrates per day okay?

Unless you are trying to cut for a competition....20 carbs a day is not good, especially if you exercise regularly. Your body uses carbs as a fuel source. If you are not getting ready for some kind of body competition, you should really eat more. You should eat 50-100 carbs a day depending on your old diet and how many carbs you ate on it. If you want a low carb diet, you need to eat a carb in the morning, like a banana or something, and a carb after your workout/dinner. This will give your body enough energy to make it through the day and you will actually be able to stick with the diet. A diet that is less than 20 carbs a day will be extremely hard to stick with because your body will be dying for carbs.