You see, it takes calories to burn calories. That is, that low-fat yogurt may only have 50 calories, but you might burn 10 calories digesting that yogurt. And if you drank any water to wash that yogurt down, your body would use more calories to digest both the water and yogurt.
So of the 50 calories that you've consumed, you may have only gotten 30 calories from it -- or less. This is why low-calorie snacks would leave you hungry later on!
Well, let's make the meal bigger. Let's say you've eaten a hamburger -- a home-made hamburger. One burger patty has about 240 calories, and when you include the bread, you could consume nearly 500 calories. Ouch! However, the fat and protein content of that burger requires lots of calories to break down. Your body might end up using 50 calories or more just to digest that burger.
The key is in the digestion. Your digestion makes up a good portion of your metabolic rate. That is, by simply eating food you could burn calories.
Think about this. When you chew, you are using your jaw muscles, which are POWERFUL and they require calories to work. Then when you swallow, your tongue and esophagus are at work to push the food to the stomach. Then stomach creates acid to further break down the food. Once the food is broken down, the stomach pushes the food into the small intestine. The small intestine pushes the food for about 20 feet until it gets pushed through the large intestine. The large intestine pushes the food to the rectum where you start burning calories trying to poop it out!
Whew! That's a lot of work -- and a LOT of calories that the digestion system used to process all that food. So if you only ate a hamburger and washed it down with water, it could take your body about 500 or more calories to process that food and it all starts with your mouth. You barely got ANY calories from that one burger!
HOWEVER, let's say that you ate a small bag of gummy worms -- which has about 770 calories! Gummy worms are simply sugar with some thickening agents. It doesn't take your body much work to digest that sugar. Barely any of it would make it to the large intestines because the candy would simply dissolve in the stomach and get absorbed in the small intestines.
This is why you're likely to get fat from candy than from a hamburger. It takes lots of calories to digest a hamburger, but barely any calories to digest candy.
A normal size apple may only have 50 calories, but if you also eat the skin, then your body has to work harder to break down that skin. The skin is mostly fiber, which the body cannot digest. However, the body still processes the fiber in other ways, such as using it to clean up your intestines. But because of the fiber content, you use up more calories to digest an apple than you would if you peeled the skin off.
So of the 50 calories that is in an apple, you've probably used just as many calories IF NOT MORE to digest the apple with the skin.
Beans and rice have a considerable amount of calories, but they are also HIGH in fiber and protein. This means a lot of work for the body to digest this food. Almonds are HIGH in calories (just 1/4 cup could have almost 200 calories), but the high protein, fat, and fiber content require a load of calories from the body to digest.
When you look at the number of calories on your food, those are just the calories you start with. As your body digest this food, the calories would decrease. If you've started out with 300 calories, your body may only get HALF of those calories or less because of the digestion process.
Now, let me admit that I'm just throwing out number estimates. There is no way to truly measure how many calories you could burn when digesting a food. Some of you may come up with higher or lower estimates of how many calories you burn when digesting food.
However, you could get a strong idea of how much energy your body uses when digesting food by seeing:
- How much heat your body produces when digesting food
- How tired you get after eating a meal
- What kind of food you've eaten
When your body digests food, it creates heat called diet-induced thermogenesis. There are plenty of machines where you could measure heat in the body. If you ate a big meal and I've scanned your belly area, I should see reds, oranges, and yellows, colors that show different degrees of heat. The more heat your body produces, the more energy the body uses -- energy that comes from calories. That is, the hotter your belly gets, the more calories the body is using to digest your food.
Feeling fatigue after a big meal? That means that your body is using TOO MUCH energy to digest your food. This explains why you're always getting tired after lunch. You tend to eat too much food or too much protein during lunch. Protein is a hard nutrient to break down, requiring lots of energy from the body.
Then there's the type of foods you're eating. If you're eating a ton of meat, then your body requires a ton of energy to break down due to the high protein content.
Next time you eat a big meal, don't freak out about getting fat. However, do freak out when you gorge on sweets. Yes, the sweets will make you fat if you go crazy with it. Simple sugar foods are high in calories and it takes the body very few calories to digest them.