The subject pretty much says it all.
My morning cream cheese schmear says “Calories 45, Calories from fat: 30”
Does it make a difference to my body that 30 of these calories are from fat? Are the 15 non-fat calories going to be used differently than the 30 that are?
A calorie in is a calorie in, basically. Some foods are broken down slower than others, which might lead to different effects, but that has more to do with sugar structure, not calories. I think the idea behind breaking out the calories from fat are to help people proportion their fat intake as a percentage, ie, 40% carbs, 30% protein, 30% fat, or whatever you’re shooting for.
It matters this way long term:
If you are restricted to a diet of 2000 calories, if you get alot of those from fat, chances are you are going to max out your calories long before you feel satisfied.
If you get your calories from nutrient dense food that are full of protein and/or complex carbohydrates, such as grains, fruits, veggies and beans, then you will probably feel stuffed and satisfied after meals and at the end of each day.
Basically it’s saying, two-thirds of the energy in this food comes from fat. Overall, getting two-thirds of your energy from fat is not a good thing, as it means you are not likely to be getting enough carbs and protein - or at least, if you are, then you’re getting way too much fat as well!
The calories are something of a red herring - it’s really just a more useful way of comparing how much fat the food contains.
E.g., imagine food A was 30% fat, 70% water (mmm, tasty). Food B was 30% fat, 10% protein, 40% carbohydrate and 20% water.
Both foods are 30% fat, so the nutrition information would say “100g contains 30g of fat” or whatever.
But Food A has 100% of its calories from fat, whereas Food B has only about 57% of its calories from fat.
(Fat has 9 calories per gram, protein = 4 cal/g, carbohydrate = 4 cal/g. So total cals = (30 x 9) + (10 x 4) + (40 x 4) = 470 cal per 100g, of which 270 cal is from fat.)
Yes. Specially, they will be used very differently than the calories from proteins, which should “never” be used. Also, while carbs and fats can be turned into each other, neither carbs nor fats can be turned into proteins (not without stripping other proteins of the “extra” materials). Carbs and fats are both made of CHO; proteins have N and S as well.
Fat is the part of food that goes faster into “long term energy storage” (fatty tissue); carbs can be converted into fat for long-term storage (also into glucogen for shorter-term storage in the liver) and they’re the body’s main “fuel”; proteins are building-blocks, won’t be used for energy storage or to obtain energy unless you eat nothing-but.
This is all sort of exagerated and simplified but my idea is to give you the basic biochemical notions, not the whole course.
And if you eat nothing but protein, you’ll be constipated and your bowel movemets will be like passing rocks. I believe it also plays hell on your kidneys.
Carbs and proteins have four calories a gram. Fat has nine.
You can eat double the amounts of carbs and proteins and still eat fewer calories than the same amount in fat.