TEF vs. Calories

calories
tef
(PJ) #1

(I could find no logical place to put this thread so I’m stuffing it in the new section.)

I’ve been reading about TEF (thermal effect of food). In short this is how, each kind of food, takes the body a certain amount of energy to digest. Meat takes more energy than fat. Different kinds of protein (e.g. sirloin steak, vs. cheese casein, vs. pea, vs. whey protein powder) take a different amount of energy to digest. (And have a different % of absorption but that is a different topic.)

I feel like I missed a memo on one little area of this though:

To hear it discussed, you would think the big goal in life here is to have the body actually lose as much energy as possible in the process of digesting its food. Which if you’re trying to lose weight I guess makes sense. Or if you want to be able to eat a few more calories, I guess it makes sense. But on that calories note…

If eating too little energy (under-calories) is such a bad thing; why would we want our body to lose energy trying to digest what we feed it? Let’s say over the course of a high protein day you actually lost 300 calories due to TEF. Does the body “not count that” as the same kind of deficit as eating hypo-caloric?

It sounds like mob accounting to me. “Oh, I didn’t take that money from your pay, it just cost that much money to process your paycheck.” :rofl: To the end-user (body in this case) it doesn’t seem like it would make much difference why or how the deficit came about.

So I guess my point is, if eating too little energy is a problem, why isn’t eating in a way that ‘costs the body energy’ also a problem? Either way, the body only has X quantity of calories from your overall intake “to use for building your body.” It seems reasonable that it would, technically, need slightly more if the ‘cost’ of its intake was more. Whether that’s due to your eating less or it taking more energy to digest sirloin than butter it still means the body has less energy.

I guess it just seems to me that there are a number of sort of… assumptions or factoids that are used in one context in one way (low energy intake: bad!) and the same result is used in another context in a different way (energy intake has chunk subtracted [=“lower”] for TEF: good!).

(mole person) #2

Not to mention the increased oxidative stress. This is similar to why I don’t have any interest in increasing my metabolism any amount beyond what I need to feel good, have plenty of energy, and be warm. I see only detriments.

(Central Florida Bob ) #3

FWIW, PJ, I think you’ve hit on a perfect example of the inconsistency of calorie theory. In my mind, thinking about calorie theory is a waste of calories.

I’m a strong advocate of hormonal theories as opposed to strict energy management because of inconsistencies like this. I remember reading around 20 years ago in a cycling magazine about a study where they put some cyclists at the US Olympic training center on strictly measured diets to get their power to weight ratio up (by reducing weight). The results didn’t come out as expected. The cyclists didn’t lose the weight the calculations said they would and the researchers said it was because their activity when off the bike went down to make up for lower calories; specifically because they moved less in their sleep. They calculated that moving their legs in their sleep accounted for the calories the cyclists were not allowed.

It’s one of my favorite stupid studies. It protects the theory (CICO) while showing it’s totally out of your control. By definition, you can’t control how much you move in your sleep, so if you do that often-recommended “just eat a hundred calories less a day and move more” you can’t possibly control that. It can’t work.

I read that as saying in the range of caloric intake we can achieve, let’s say zero to twice what we need, the ends of that range matter, the middle is out of our control. If you eat zero long enough, you lose weight and die. If you eat twice what you need long enough, your weight goes up until it’s stable. In the middle ranges, where we live, your output changes to match what’s coming in, or you match your intake to what you’re expending. If you eat less, your body saves what it can to preserve itself. It’s not “shutdown mode” like on or off, it’s throttling back.

I know there are people who say they cut back or add a few calories every day and their weight goes back to normal. I think they’re a small percentage of the population, and I think that if your system doesn’t adapt to your food intake that’s a defect that natural selection would select against. What seems better for a population with low or erratic food availability: dynamically adjusting energy output during times of scarcity or abundance, or burning the same amount regardless of the environment? Which may be saying that people who can adjust their weight by “not having one slice of toast a day” came from an area where there was always food available.

For most people, we don’t gain weight because we’re eating too many calories, we’re eating too many calories because we’re gaining weight. Likewise for losing.

(You've tried everything else; why not try bacon?) #4

Scientists make a distinction between the “thermal effect of food,” which is a measurement of the degree to which our metabolic rate increases after we eat, and the “energy cost of metabolism” which is a calculated value based of the reactive potentials of each chemical reaction involved in metabolising a fatty acid, a carbohydrate, or a protein.

The thermic effect of food on a given person is a totally individual measurement, and will vary, not only from person to person, but also within the same person according to circumstances. The energy cost of a metabolic reaction, being a calculated number, does not vary. Because of the reactions involved, proteins carry the highest metabolic cost, requiring a fair amount of energy to reduce to ATP, carbon dioxide, and water.

The energy cost of metabolising a carbohydrate is pretty much the same as that of metabolising a fatty acid (although I seem to remember that a fatty acids yields a few extra ATP molecules in comparison, but don’t quote me) and is quite a bit lower than that of metabolising the average protein. This is a good thing, because under normal circumstances, the body will pick either of the less costly pathways and reserve proteins for structural uses. But the protein pathway is still available for emergencies.

It is not entirely clear from my reading whether or not the energy cost of metabolism is part of what is measured when they measure the thermic effect of food in someone.

(PJ) #5

Interesting, thanks for spec’ing out the two different things. I think I got the impression that the ‘cost of metabolizing a certain compound’ WAS what they call TEF, so I guess I misunderstood. I hadn’t considered a metabolic effect separate from that.

(PJ) #6

You’re right that’s ridiculous. I think a lot of the problems we have is that instead of saying, “Let’s give the body what it really needs,” we often say, “Let’s find a way to hack this so we can NOT give the body what it needs, OR give it what it doesn’t want at all, but prevent its natural response to that condition!”

Like pills that make you less hungry. WTF man, you’re hungry because your body wants to eat! Maybe feed it steak instead of hotpockets if you don’t want eating to make you fat!

I feel like hacking calories (I’m not saying a “loose” attention to their range is bad, only any kind of obsession with it as the primary cue) is on the same spectrum. The body doesn’t eat for calories anyway. It eats for nutrients. This is where I think Marty at optimizing nutrition is on the right track.

(Robert C) #7

Hi @RightNOW,

This is a note about your posts generally - not this particular one.

I think you might be looking at the body as a machine - it is not.

For example, calorie restriction brings about a response of adaptation to a lower food environment - but a lawnmower just runs out of gas (petrol for our UK people) and freezes. I have not seen a human run out of fuel and freeze.

As well, no one thinks about creating a lawnmower that maximizes fuel usage. But, in our world’s current food environment - this may be the best tactic for overall health.

My opinion is that maximizing TEF would lead to overconsumption of protein but, this effect is small in comparison to actually just taking a big step back and dealing with a well formulated ketogenic diet (with high quality foods) and some TRF or actual fasting.

(PJ) #8

Thanks Rob. Good point.

I’m on an 88 hour fast right now, a short one compared to those I normally ‘formally’ bother with (aside from 18/7 which is fairly common). And protein is my primary focus now. So I’ll just have to do it and see how it turns out. N=1 and all. :slight_smile:

(Michael - When reality fails to meet expectations, the problem is not reality.) #9

Things like TEF, RER, energy balance, even calories don’t necessarily reduce to machine mechanics. Reduction to mechanics is precisely the reason CICO and ‘move more eat less’ don’t work. TEF etc. are all, however, useful tools for examining and understanding metabolism and how it works. The body may not be a ‘machine’. It is, however, a biochemical processor and the chemistry of the various processes is amenable to examination and comparison. Just such chemical examination and comparison has enabled a very good understanding of much of human metabolism.