What Makes Up a Calorie?

Calories are a unit of energy that our bodies use to fuel our body functions and movements. All the calories that come from food come from three sources, well actually four; fat, protein, carbohydrates and alcohol (we will just focus on the BIG 3). For each gram of each of these macronutrients (can you say that with me? All together Macro-nutrients) there is an associated amount of calories. For each gram of fat there is about 9 calories (there are probably some decimals) , one gram of protein = 4 calories and one carbohydrate is 4 calories, alcohol is 7 calories per gram. So yes you can have 2 grams of protein and carbs and still have less calories than you would for 1 gram of fat. So when you see on the label calories from fat this is where it comes from. They could also have it labeled calories from protein and calories from carbs.
Let’s use this nutritional fact as an example

18 grams of fat= (18*9)=162 calories from fat
4 grams of carbs=(4*4) 16 calories form carbs
4 grams of protein =(4*4) 16 grams of protein
194 total calories

You may notice a small discrepancy in the calories through addition and those shown on the nutritional facts that is usually because the manufacturer can remove insoluble fiber from the total calories per serving, because insoluble fiber passes through the body without being converted to energy, so they don’t need to show it.

As far as the ratio between the 3 for your daily caloric intake the numbers vary, and ultimately it comes down to figuring out what works best for you. The general consensus between all the varying information is your carbs should account for about 50-55%, while protein should be around 20-30% and fat 15-25%. For those who are trying to lose weight the proteins should defiantly be around 30% and less in the fat intake.

Ultimately if you over consume either of the 3 macronutrients the excess calories will be converted to fat and stored for your body to use at another time(at least that’s your bodies future plan). The difference between the 3 comes from what it takes to actually convert itself to the fat to be stored. For both protein and cabs it actually takes about 25% of the excess calories to convert it to fat. Fat however only takes 3% of the excess calories to convert it. So if you over consumed 100 calories from each of the macronutrients your body would store up only 75 calories of the 100. While the fat calories would hoard 97 of those calories. So if you’re going to over indulge make sure you do it with carbs and proteins.
Finally I found this, check it out. It shows various pictures of food portioned out to 200 calories. It might help when you just want to get full and not consume lots of calories.

http://www.wisegeek.com/what-does-200-calories-look-like.htm