Ok, thanks to the typical numbnuts and naysayers who of course never provide any information to rebutt, I'll go ahead and break down the basics about why this works. Also -- no it's not hard or a lot of effort. Yes it is more effort than let's say, um grabbing a donut at 10:30, eating a cheesteak and fries for lunch, washing it down with 5 sodas and then running throught the drive-through at 7:30 on the way home.
When you eat carbs, they are broken down and end raising your blood sugar level. To counteract this, the pancreas secretes Insulin which will then cause this to go to one of 3 places: muscle glycogen, liver glycogen or Fat. One of the factors involved is how high of a Blood sugar spike you get, and one of the basic factors in this is how fast the Carb is broken down and become blood sugar. While not the be all and end all, the Glycemic Index (GI) of foods gives a good starting point, in helping to show why foods that have a good deal of natural fiber take longer to break down, which in turn provides a slow steady amount of blood sugar, thus not causing huge swings of your Insulin levels. If your blood constantly has a high Insulin level, this will cause you to store fat, and of course overtime if this becomes Chronic --- well the name for the condiition is Diabetes. Something you don't want to develope.
Hmm... ok, so when you have huge spikes in your blood sugar, that is bad --- hmmm, well maybe then a habit like, let's saying eating 2 huge meals a day, might not be the most healthy way to gain the nutrients you need? Perhaps the huge swings in blood sugar and insulin levels might explain why, despite exercising, one finds themselves with a spare tire they can't lose? And also perhaps explain why they're not feeling very good through the day, and experiencing low energy, and cravings and hunger pangs?