Calories and body efficiency...

[Oualawouzou]

Hello everybody,

Here's something I've been wondering for a while.

I understand the human is a great but imperfect machine. Although it is good at extracting energy from food, it isn't perfectly efficient.

(disclaimer: what follows is what I've heard, I can't vouch for the veracity of those claims) Some diets, such as the infamous Atkins (btw, is it me or is it finally falling off the radar?), rely precisely on the body's inefficiency. If i understand Atkins right, it posits that the body can only process a certain amount of fat per day, whereas it can process about as much carbs as you can put in your stomach, so carbs are the ennemy, whereas you can gorge on fat and be ok (though with maybe some stomachache, but that's beside the point).

Which leads me to my *real* question... Pretty much every food item sold has to have a helpful little chart explaining how many calories are contained in a given portion, and break the whole thing down in carbs, fat and proteins. Usually, when people want to monitor their calory intake, they look only at how many calories there are in a portion, not at how it is divided.

So, all in all, how much trust should we put in those handy little charts? Keeping in my mind that my body isn't 100% efficient, and that different sources of energy will be assimilated with different success by my body, can I in any way rely on the info displayed on packaging?

Yeah, so it's more down to earth than most topics discussed here, but not every thread has to be about eating magnets for breakfast in order to re-align the moon's axis in the quantum dimension of whatever.

Thanks!

 

[ChristineR]

There are a lot of things going on. Every apple is different, so you can't assume that the chart is perfect. It takes a certain amount of energy just to digest your food, and that depends on whether it is protein, carbohydrate, or fat. Protein takes the most (I believe), fat the least.

All food has some indigestible components, fiber being the most important one. Calorie content is determined by burning the food and measuring the heat given off, and ths will vary depending on how fiber is accounted for.

There is a limit to the amount of food you can process in one day, and the usual limiting factor is your vomiting. There are diets that rely on excessive fat intake which gives you severe diarrhea, but I wouldn't class Atkins as one of them.

Atkins mostly relies on ketosis, which is an excess of ketones in the blood, which leads to various physiological changes useful for a starving person. Ketones are a byproduct of your metabolizing your own fat. In the absence of carbohydrate in the diet you need to convert ingested fat and protein into to body fat and then burn it, which is both inefficient and productive of ketones.

So to go back to the actual question, the calorie charts aren't magic, but they are about as reliable as you're going to get. If you eat a 1500 calorie diet you're going to get all sorts of adjustment factors that you can't control, but the ratio of protein/carb/fat is relatively minor. Probably the most important is your body temperature. People who diet often get cold and stop losing weight despite reduced calorie intake.

 

[Myriad]

When I decided to lose weight a few years ago, I successfully applied two rules of thumb:

1. A Calorie is a Calorie.

2. However, paying attention to the Glycemic Index is also useful.

The usefulness of Glycemic Index when counting calories (or counting something more or less equivalent, like food group servings per day or Weight Watchers "points") is that the lower glycemic index foods you eat, the less likely you are to get "hungry" between meals. And by "hungry" I don't mean just real empty-stomach hungry, which I find is pretty easy to resist until mealtime, but also, the kind of all in your head craving where you can't stop thinking about a snack.

Note that most most fats and proteins are also low glycemic index. After researching a lot of confusing and seemingly contradictory information and study results, I'm convinced that that's the real reason (and the only real reason) why Atkins and similar low-carb diets work for some people. Others have apparently reasoned the same thing, hence the more recent (and probably healthier) diets like South Beach that incorporate low-glycemic-index carbs.

This site has always seemed to me to have sensible advice, including sensible reviews of many brand-name diet plans: http://www.diet-i.com

Good luck!

Respectfully,
Myriad

 

[skeptifem]

The body is extremely efficient, different calorie sources (fat, protein, carbs) are better at different things, so the body acts accordingly. The reason carbs are avoided in atkins or other low carb diets is because they are generally not very filling, and are converted easily into energy for immediate usage or for storage, carbs have priority for storage (body fat) over fats. Most carb heavy foods have little else besides calories in the way of nutrition. You can eat carbs all day and not get full, and that is generally a reason for gaining body fat. Protein is very filling and has less calories than carbs or fat, so its an obvious choice. Fat has many important functions in the body, and is used for those essential functions before being stored. Good fats are an important nutrient and promote health. The atkins diet is pretty extreme, carbs can be good if you eat the right kinds. Choosing things like fruit to get carbs with other nutrients is a good choice, and fiber makes it a bit more filling, and just choosing whole weat and whole grain products make sure that you arent hungry a half hour after eating something carb heavy. Carbohydrates are nutrient just like protein and neither should be cut down too much, they all have their place in a healthy diet.

I like this website a lot, its centered around weight training but it has many other articles that are useful,heres a basic nutrtion article:


http://stumptuous.com/cms/displayarticle.php?aid=6

 

[baron]

Which leads me to my *real* question... Pretty much every food item sold has to have a helpful little chart explaining how many calories are contained in a given portion, and break the whole thing down in carbs, fat and proteins. Usually, when people want to monitor their calory intake, they look only at how many calories there are in a portion, not at how it is divided.

So, all in all, how much trust should we put in those handy little charts? Keeping in my mind that my body isn't 100% efficient, and that different sources of energy will be assimilated with different success by my body, can I in any way rely on the info displayed on packaging?

What do you mean when you say "trust?" You can almost always rely on the charts being accurate. Other than that, it's up to you to interpret them correctly. Only a fraction of the population can do this properly, which is why in the UK I believe simpler "traffic-lighting" labeling is being tried in some stores. This is not necessarily a criticism of the public at large (although I suppose it is in part) because we are constantly fed a barrage of food-related nonsense via advertising and the media.

The efficiency of your body in breaking down food is not relevant, unless you have some ailment that prevents you metabolising certain foods. There may be some variation in the rate you can break down, say, protein, compared to someone else, but as you'll never be able to quantify this the best you can do is understand what the food labelling is telling you and act accordingly.

 

[baron]

There is a limit to the amount of food you can process in one day, and the usual limiting factor is your vomiting.

True, but bear in mind that people eager to lose weight may have substantially increased their capacity for food by the act of over-eating.

 

[Oualawouzou]

Thanks everybody for the quick response. Lots of good info, as usual.

What do you mean when you say "trust?"

I meant by that, if the chart says that a portion of Food X has 250 calories, and that for some reason I'm watching my calory intake (I'm not, but that's not the point), should I add 250 calories to my intake of that day, or should I consider that my body has only "absorbed" a percentage of it?

Well, from the responses here, I guess whatever the body doesn't absorb is negligeable, so common sense + a quick look at the Glycemic Index here and there should do the work.

because we are constantly fed a barrage of food-related nonsense via advertising and the media.

Don't forget the endless barrage of "helpful" advices thrown your way if you ever manage to remotely allude to a weight concern on your lunch hour with coworkers within earshot.

 

[ChristineR]

Thanks everybody for the quick response. Lots of good info, as usual.



I meant by that, if the chart says that a portion of Food X has 250 calories, and that for some reason I'm watching my calory intake (I'm not, but that's not the point), should I add 250 calories to my intake of that day, or should I consider that my body has only "absorbed" a percentage of it?

Well, both. The numbers are only approximations as the food measured for the box was not exactly the same as the food in the box. And although there is a portion that you will not absorb, the testers did try to account for it, and of course that is a different source of error.

Ultimately when people talk about a 1500 kCal diet they mean 1500 plus or minus all the errors, so there is no point in subtracting the various waste and error calories and calling it a 1400 kCal diet, as you will then mean something different from what everyone else is talking about.

 

[baron]

Don't forget the endless barrage of "helpful" advices thrown your way if you ever manage to remotely allude to a weight concern on your lunch hour with coworkers within earshot.

Oh for sure. A new guy in our office was telling everyone about the new diet he was on. Apparently it consisted of him eating virtually nothing (400 calories per day) for a two weeks, then 800 for 4 weeks... you get the idea, nonsense. When I suggested that the best and only way to gain and maintain a good weight is to eat healthily and exercise he got quite uppity about it. "Oh, but I've already lost 10lb!" he said. I tried to reason with him but it was pointless. Needless to say, the diet didn't work and now he's around 3 stone heavier than when he started.

 

[skeptifem]

Oh for sure. A new guy in our office was telling everyone about the new diet he was on. Apparently it consisted of him eating virtually nothing (400 calories per day) for a two weeks, then 800 for 4 weeks... you get the idea, nonsense. When I suggested that the best and only way to gain and maintain a good weight is to eat healthily and exercise he got quite uppity about it. "Oh, but I've already lost 10lb!" he said. I tried to reason with him but it was pointless. Needless to say, the diet didn't work and now he's around 3 stone heavier than when he started.

lol. on eating disorder boards they call that 2-4-6-8. its supposed to keep your metabolism from going completely away. it starts at 200 though.

 

[pgwenthold]

The body is extremely efficient, different calorie sources (fat, protein, carbs) are better at different things, so the body acts accordingly. The reason carbs are avoided in atkins or other low carb diets is because they are generally not very filling,

Pasta is extremely filling, I have always thought. As is bread. And potatos.

In lean times, people eat a lot of carbs, mainly because they are filling. A baked potato can be a meal. Dad always used to say, "They stick to your ribs"

 

[bobdroege7]

those little numbers on the labels are bomb calorimeter numbers, so that is the maximum amount of energy in the food. Since the body has various pathways of varying efficiency, you will always get less than that amount of energy.

I don't think Adkins ever understood why low carb diets work and most of the Nutritionists that denounce it don't understand it either.

Your body can burn fat with carbohydrates present or without carbohydrates. With out carbohydrates, the body gets less energy from fat and thus has to burn more.

the body also has difficulty storing fat without carbohydrates present. Triglycerides, 3 carbon backbone with aliphatic carbon chains attached are manufactured from glucose which is split in two during glycolosis to provide the 3 carbon glycerol backbone for triglycerides.

Adkins is right to say that refined sugar and bleached flour are two of the worst things you can put in your body.

Watch out for whole wheat bread, check the label and make sure you are not eating refined flour colored with molassas.

Adkins was pretty funny to say that trans fats are called trans because they are transformed in the manufacturing process. True but not true.

 

[Dilb]

those little numbers on the labels are bomb calorimeter numbers, so that is the maximum amount of energy in the food. Since the body has various pathways of varying efficiency, you will always get less than that amount of energy.

In Canada, at least, those numbers are calculated from the other information. 4 Cal/g for digested carbs (i.e. not including fiber), 4 Cal/g for protein and 9 g/Cal for fat, and some others. This is slightly annoying when applied to small servings, as if there's less than half a gram it's rounded down to zero. Meaning oil is 'fat-free' if the serving size is less than a gram, which is the case for cooking oil sprays. See url=http://www.pam4you.com/pages/products/baking/index.jsp]PAM[/url], the second set of nutrition facts for an example.