Anyone who has ever tried to lose weight knows all about calories and how they are the bain of the diet industry. The idea is simple, if you eat fewer calories then you expend during your daily existence you will lose weight. The problem is that while most people understand this concept it seems the majority of us have a hard time accomplishing it. Probably the major reason is most people do not understand how their metabolism works in relation to the type of calories they eat.

Calories are the fuel that makes our body's run. Without adequate calories our metabolism slows down and our body systems will begin to malfunction. This is not good because as our metabolism slows the body begins to cannibalize its muscle tissue for energy while hoarding what fat stores it has and converting any excess calories it can find back into fatty storage. If you've ever tried a crash diet this is basically what happens. The last thing anyone wants when attempting to lose weight is a slow down of their metabolism which will render any diet and weight loss goals nearly impossible.

So how do negative calorie foods fit into all this? And what is a negative calorie food? Contrary to what it sounds like they are not foods that have a negative amount of calories. All foods have calories; some more than others and depending on the food these calories are metabolized in different ways by the body's digestive system. The theory behind a negative calorie food is quite simple actually. It is believed that some foods use more calories during the digestive process then they actually contain. Now as odd as that may sound there is some truth to the idea behind negative calorie foods.

Before we explain why it would take more calories to metabolize some foods and not others let take a quick look at how calories are used. Let's say you eat a piece of cake before bed that contains 350 calories, and most of that is all from sugar. Your body expends 75 calories digesting that piece of cake leaving you with a net gain of 275 calories. Where do those extra calories go? Straight to fat storage. Now let's say you eat a negative calorie food like a grapefruit (some of you are probably familiar with the grapefruit diet fads) that has 35 calories. If it takes the body 90 calories to digest and metabolize that grapefruit your body will have burned an extra 55 calories with no additional work from you.

How does this happen? Most negative calorie foods fall into the fruits and vegetables families. Because fruits and vegetables are nutrient dense and contain lots of fiber the digestive system must work extra hard to extract these nutrients for use by the body. The high fiber content also contributes to the negative calorie phenomenon because fiber digestion is one of the most energy intensive processes the body undertakes when it comes to metabolizing food.

This brings us back to the point moms used to belabor upon their kids about eating foods that are good for them. That's what it's all about. In this day and age many of the foods we consume are not that good for us. They contain mainly empty calories that the body quickly and easily stores away as fat, expending very little energy in the process. And with our more sedentary lifestyles the vast majority of people simply do not expend more calories then they consume while the food we do eat has very little nutritional value. If you are looking for a way to increase your metabolism and lose some weight it might be wise to heed the words about eating nutritious foods that moms used to speak in days gone past. You are what you eat.