Today we're going to focus on carbohydrates.
Most people think of carbohydrates as bread, pasta and rice, but they include more than this and are divided into 3 catagories: sugar, starch and fiber.
Sugars are either monosaccharides (mono = one, saccharide = sugar) like glucose or fructose found in fruit, or disaccharides (di = two, saccharide = sugar) like sucrose, table sugar.
Starches are polysaccharides (poly = many), which simply means there are lots of sugar molecules bound together, these are found in potatoes, bread, rice etc. You'll notice that starches are just sugar molecules bound together.
The less molecules a carbohydrate has, the quicker it is broken down to use as fuel. If you were in the Great Manchester Run this weekend, you would find a banana or sugary drink useful around the the 7k point to give you some easily digested energy to help you finish the race. If you were sat at home watching the Britain's Got Talent repeat, chances are that same banana would have just been stored as fat. Carbohydrates are used to create energy for the body to be used for movement. The quicker a carbohydrate is broken down the sooner it is available to use, but if you don't use it, it will get stored as fat with the intention of being used at a later date. As you can see banana's aren't bad, in some situations they are a good choice, but in others not so much.
If you're not doing prolonged physical activity you have little need for fast acting sugars, so you want to stick to starches and limit sugar intake. How much you need will depend on how much movement you do throughout the day. Most people will use 200 to 300 calories a day moving around (this would increase if you went to the gym or did any type of exercise), so if you weren't trying to lose fat, your carbohydrate intake should match that. If you are trying to lose some body fat, then you want to eat less carbohydrates than you need. This will force your body to breakdown your stored fat in order to fuel your activity. This can be done by either increasing your activity levels or decreasing your carbohydrate intake, or ideally a bit of both. Starches are the best option as they are released slower, so are less likely to get stored as fat and they will fill you up for longer, because they take more time to break down.
As you can see sugar and starches aren't bad and the only thing that makes one better than the other is the situation you are in. Eat your carbohydrates wisely and make sure the amount you eat matches your goals.
The third type of carbohydrate Fiber is strings of sugars, like starches, except that the bonds between the sugars cannot be broken down for energy. Fibre is found in most vegetables and is generally good for your health, but some fiber is better than others. The fiber found in vegetables and tubers (potatoes, sweet potatoes etc) are fermentable (I'm not convinced fermatable is a word, but I'm going with it), whereas the fibre found in whole grains aren't, as much.
Fermentable fiber is important for the health of our gut. We have beneficial bacteria in our gut that uses fiber for food. These beneficial bacterias are pretty useful for detoxifying harmful compounds in our food and water, they are also crucial for an effective immune system and can help prevent diabetes and other autoimmune diseases. So we want to keep these guys happy and well fed, grains won't do it, so make sure you get your fiber from fruits and veg.
Hopefully this clears up the confusion about carbohydrates. Carbohydrates aren't bad, you just need to choose the right types in the correct amounts.