Sorry for the poorly phrased title.
All the diet questions that pop up on the boards got me wondering this. If I understand correctly, calories come from 3 basic categories: fat, carbs, and protein.
Is it possible for say a 4 oz. piece of dessert/meat to carry more calories than say 4 oz. of pure sugar?
Lots of fluid in meat, displaces the calories. Fat is 9 calories per gram, carbs and protein are 4 per gram. Fat is pure calories.
A little more clearly: Sugar is ~4 cals/gram. Fat is about 9 cals/gram.
So a dessert that was pure fat (think whipped lard + a smidgen of sugar = non-diet Cool Whip) would be close to the theoretical maximum. It’d also be about twice the calories of pure sugar of the same weight.
Alcohol is also a source of calories, at 7 calories/gram, is it not?
I’m pretty sure alcohol falls under the ‘carbohydrate’ category.
Except that it is whipped and full of air. I suppose it makes little difference ina calories/gram measurement, but in a calories/volume measurement it makes a big difference. A vegetable oil/aspertame mixture would be about as dense as you could get. I say aspertame rather than sugar, because it takes so little to sweeten it allowing you to pack more calories of pure fat.
I wonder what chemical has the most digestible calories per CC and per gram? My guesses would be glycerin, ethanol or stearic acid.
I wouldn’t guess those. Glycerin is actually used as an artificial sweetener, because it has about the same amount of calories as table sugar but a lower glycemic index. Ethanol has more calories than carbohydrates, but less than fats, and it’s not digested very effectively by the body, which is why heavy drinkers tend to lose weight. Stearic acid has 9.5kcal/gram, but it’s also not digested very well by the body, so the amount of calories you’re getting from it is going to be much lower.
Sugar alcohol molecules are usually separated out at 7 calories per gram. They normally aren’t included because there are so few of them in normal foods.
Vegetable oils are pure fat and have about 120 calories per tablespoon. Can’t get denser than that.
The OP was talking about “calorie density” that is, calories per unit weight. It’s a common but informal use of the term “density”. Gotta be careful to not confuse that with calories per unit volume, or weight per unit volume.
Well I guess I’m not familiar with what the standard terms are for “calorie density”. If that is what the term means, then clearly you are right. On the other hand, when I’m trying to lose weight, I’m more interested in calories per volume, since high volume foods are more filling. I wasn’t aware that calorie density was well defined.
I picked glycerin, because I figured it would be easy to digest so the body would absorb the calories very efficiently. Obviously, if it has the same caloric value as sugar, it isn’t the most calorie dense compound. I’m not certain that it’s rating on the gycemic index has anything to do with the number of calories the body absorbs.
I should have figured that ethanol didn’t qualify since it is less dense than fat. Of course, as I stated above, I’m more interested in calories per volume, but if the 7 Cal/g quoted above is correct, it isn’t either.
I picked stearic acid, because, at least combustion wise, it should be the most calorie dense per volume. More hydrogen and more carbon means it generates more water and more carbon dioxide. I don’t know enough about the digestive system and biochemistry to know how much of it is absorbed. Are you saying that we excrete a large percentage of the stearic acid we eat? How do we excrete it?
What about a glass of pure Adenosine triphosphate?
I don’t think that ATP would survive the digestive system in tact. The stomach acid should hydrolyze those phospates if the kinetics are right.
What about cholesterol?
ATP isn’t very energy-dense. It’s useful to move energy, but not to store it. One molecule of glucose is going to produce the energy to charge 36 ATP (that is 36 ADP -> 36 ATP). Since ATP is even larger/heavier than a glucose molecule, I’d guess that it’s less than 1% the energy of glucose.
(And here I thought all that biochem would never come in handy after I moved into the accounting field).
I think in practicle terms 9 calories per gram is the limit.
For quick calculating I remember these figure
Fats and oils 9 calories
Cereals 3-5 (even true of rice and pasta because the served portion is much heavier than the dry weight)
Cheeses 4
Fatty meats 3-4
Lean Meats 2-3
Fish 1-2
Milk 0.8
Egg (1) 0.7
Yoghurt 0.6
Low fat milk 0.5
Most fruit and vegetables .1-1
The things that most surprise people when you point these things out are:
Dairy products are far lower in calories than they assume.
Virtually all biscuits have the same calorie density regardless of variety. They are shocked to find that crispreads, rice cakes and sweet biscuits(cookies) are much the same.
If you shrink the size of your meat portion you can substitute huge amounts of vegetables. For instance every ounce the average meat portion is cut by you can add 5 times the weight in potatoes.
I don’t understand what you mean by these numbers. Are you just saying that many foods have a high water content?
Ahh so ATP wouldn’t survive, and isn’t very energy dense. I think I understand what it does a bit better now thanks. ATP is like a battery, doesn’t hold much energy but keeps it in a convenient form for use. Sugar is like gasoline, energy dense. The cell burns sugar to charge ATP batteries.
I suspect ATP might survive digestion, at least in some form. ATP is one variation of a pretty fundamental molecule that has multiple uses throughout biochemistry - for example, it’s turned into adenine for use in DNA/RNA and cAMP (cyclic adenosine monophosphate) for use a neurotransmitter.
The battery analogy is a pretty good one. I always thought of them like static electricity on the tip of your finger - good for one little zap before they have to go back for more.
My chemistry is rusty, but isn’t the point of adenosinetriphosphate (ATP) that it doesn’t need a whole lot of encouragement to turn into adenosinemonophosphate (AMP)? That’s what makes it a good battery; unlike sugar you don’t need to do a bunch of work to get it burning. I suspect a gob of ATP in the stomach would find some excuse to turn into AMP quickly.
But at any rate, I doubt that body cells are going to be doing much absorbtion of ATP, either in the lining of the digestive tract to move it into the bloodstream, or anywhere else in the body once it is in the bloodstream.
If this refers to my preceding post then yes that is basically how it boils down. For example from my pantry at the moment:
Calories per hundred grams
gms protein
gms fat
gms carbs
gms fibre
gms other including water, ash minerals
oats low fat milk **yoghurt ** pasta salmon bean salsa potatoes
395 50 ** 58 ** 350 ** 350 ** 84 81
**13.5 ** 3.5 4.5 15.0 59.5 4.0 3.0
**8.7 ** 1.5 0.8 1.0 11.2 0.2 0.0
54.6 5.0 **6.3 ** 75.0 0.0 13.2 17.0
12.2 ** 0.0 0.0 0.0 0.0 4.8 3.0
11.0 90.0 ** 88.4 ** 9.0 ** 29.3 77.8 77.0
the pasta is wholemeal if that matters.
If you browse around here you will soon see the trends.