Most people trying to lose weight have heard the recommendation to decrease their intake of high-carbohydrate foods, such as sugary foods, bread, cereal, pasta, etc., but a lot of people are not aware of why this recommendation is so critical to burning fat and losing weight. After all, even some doctors think that all calories are the same and the only thing necessary to lose weight is to eat fewer calories than you use up through exercise and daily activities. Due to certain hormones though, not all calories are handled the same way by the body, and the calories from carbohydrates are much more difficult to burn than the calories from other types of foods,and a high carbohydrate intake certainly makes one prone to storing fat and not burning it.
At the heart of the matter is the hormone insulin. The function of insulin is to stimulate the cells to take up sugar from the bloodstream (when blood sugar is high, as it typically is shortly after eating) and store it for reserve energy.
This extra blood sugar is first stored as a compound called glycogen in the muscles and liver. Glycogen can be quickly converted back to blood sugar when needed for energy to fuel sudden bursts of activity. The available storage space for glycogen is pretty limited, and when insulin has caused the glycogen storage to be filled up, the remaining excess blood sugar is stored as fat.
There is considerably more storage space in the body for fat than there is for glycogen. There are billions of fat cells in the body, each of which can enlarge to over 100 times it's original size to accommodate extra fat storage. As an aside, this is why it is possible to get fat again after liposuction - even if you remove many of the body's fat cells, those that remain can enlarge considerably to store fat.
Insulin is extremely powerful in its fat storage effects. In fact, not only does it stimulate fat storage, high levels of insulin block the effects of the body's fat burning mechanisms. This is where the importance of limiting carbohydrate consumption comes into play.
High carbohydrate intake (and it really doesn't need to be very high) stimulates the release of large quantities of insulin. This high production of insulin effectively prevents the body from burning fat - for 24 to 48 hours! To put it another way, simply eating about 20 to 25 grams of carbs at one time, which is about the amount of carbohydrate in just one piece of sliced bread, is enough to totally turn-off your body's ability to burn fat for up to 48 hours no matter what your diet is and no matter what you do for exercise during that period of time.
Some people mayhave doubts about that last statement as it is certainly possible to eat a lot of carbs and lose weight - for a while anyway. Notice that I said that high carbohydrate intake causes high insulin production that blocks FAT burning. It is still possible to eliminate retained water (which will produce weight loss), and it is still possible to burn calories, but the calories you do burn will not be from fat, they will be from glycogen and your lean body tissue, primarily your large muscles. As you may be aware, lean body tissue (muscle) is highly metabolically active, and if you burn that tissue, ultimately your metabolism will slow down, making it harder and harder to lose weight.
Because of the effects of insulin, minimizing carbohydrate intake is strongly recommended for sustainable fat burning and the most efficient and lasting natural weight loss. This is not to say that everyone will benefit from being on a high protein diet such as Atkins. Excessive protein intake can create its own problems that can ultimately interfere with ongoing weight loss due to detrimental effects on the liver. For the majority of people, the most effective diet is one that is high in fresh or frozen vegetables, nuts, seeds, moderate quantities of fresh fruit, and some protein from eggs, dairy, lean meat, fish, and poultry. The carbohydrates you do consume are best obtained in high-fiber forms from vegetables, fruits, seeds, and nuts, rather than from refined grains.
A few diet plans will recommend a low carbohydrate intake, yet suggest allowing yourself a "reward" of some high-carbohydrate food like a cookie or other sweet as often as once per week. I disagree with this recommendation as it can sabotage your natural weight loss program on two levels. First, as we've been discussing, the carbs will trigger a high insulin release which will shut off your ability to burn fat for up to two days. So, at once per week, you could lose as much as 8 days per month of potential fat burning - decreasing the effectiveness of your diet by as much as 25%! The other problem is that eating carbs tends to set you up for carb cravings. At the very least, such cravings will test your will-power, and they could cause you to cheat on your diet repeatedly. This could ultimately doom your diet to total failure. My advice is to save your carbohydrate consumption for special occasions only - which should be limited to once per month or less.
Hopefully you now have a better understanding of why high carbohydrate consumption is so damaging to a natural weight loss plan. If you commit to a healthy diet and avoid the carbs for 2 to 3 weeks, you will likely find that you don't really miss them after that period of time and so avoiding them becomes much easier. With a little extra effort early on, you'll find that eating a healthy diet becomes natural to you and you'll be able to reach your long-term weight goals.