the site says 216 calories, and its pretty obvious that the dicrepency between my caculation and their calculation is that they used total carbs instead of net carbs, (4x16+4x40 = ~216)
hmm? who is right? Perhaps the 216kcals from the site means the total energy contained in those beans (as extracted via calorimetry), but not total energy that can be used by a human.
I could be wrong, but I believe that most foods get their caloric total by a combustion test or an acid bath. I don’t know how exactly they do this, but I think those macro totals are mere approximations which is why they rarely add up exactly. Not to mention, the caloric values (i.e. 1g of CHO = 4 cals) is also an approximation for easier calculations.
Having said that, I find that most nutrition labels are within 1-2% of the total cals when multiplying out the macros. In your example that differential is like 20-30% off! I can’t explain that… Legumes are so low-glycemic and packed with fiber that you probably should worry more about carbs from dairy and grains.
Well, if you were a cow or other ruminant, you could digest those fibrous carbs…
Years back, in the era when I was a loser (weight loss that is) and doing ketogenic dieting (boo hiss) it was okay to subtract fibre carbs when calculating carb consumption.
I wouldn’t count the fiber as calories, as it is not digestable. You will not be getting any energy from it.
Depending on your diet and goals that would determine whether you want to include low-glycemic carbs or not.
On a side note, some people feel legumes are linked to gastrointestinal problems, which is why some cut them out. That is a personal choice but something to think about.
hiro, you’re right re the inconsistencies in reporting of macronutrients on product labels. Don’t let it bother you. As far as keeping a food log goes, just pick a method or a system and be consistent in how your record what you eat.
When I’m not eating a lot of carbs, I like to make sure I’m getting my “fiber credit,” so I’ll use net carbs. I don’t particularly care whether everything adds up at the end of the day because the end result is that on any given week that I don’t lose weight, I will make adjustments to my eating plan.
Atreides, I agree, but if you are talking about a natural food, like a vegetable, then it is a different scenario – no artificial sneaky additives involved.
[quote]vroom wrote:
Atreides, I agree, but if you are talking about a natural food, like a vegetable, then it is a different scenario – no artificial sneaky additives involved.[/quote]
very true, but this proves my point. you don’t see any net carb crap with fruits or vegetables.
The longer I do this, the further I get away from food that comes in a box.
[quote]Helix wrote:
Carbs do provide some calories. They are fermented in our colon by bacteria into short chain fatty acids which we absorb and can use for energy.
On AVERAGE fiber yields 1 calorie/gram. This is because the amount of fermentation will vary depending on the type. [/quote]
I never knew that! I heard one guy with his masters in kinesiology go as far as to say that fiber blocks calories!
Yeah, I think we should also clarify whether that is how much energy becomes available via total fermentation versus how much is actually liberated by fermentation within the body.
For example, when making beer or wine, the fermentation process takes a fairly long period of time. Longer than anything fibrous is likely to stay in your body.
Tampa-Terry, as I alluded to it is provided to the host organism(us).
The bacteria use them for energy and in the process ferment them to form short chain fatty acids(SCFA). These can be absorbed by the epithelial cells of the colon and used for energy or transported to the liver via the portal vein.
I have seen the number at between 1-1.5 cals per gram. It is not exact because this is an average across all types of fiber. Some are fermented fully and will yield more like 2 cals/gram while others will not be fermented at all and yield nothing.
I have to agree that the whole idea of Net Carbs is pretty ridiculous on non-whole foods. I think they arbritary just defined it too conviently leave out having to mention alcohol sugars, which is pretty much bunk…
but then theres whole food like lentils, where theres just so much fiber that it makes the caloric calculations just seem much too off.
now theres this stuff about fermentation and that soluable fiber can be used as energy (and then that begs the question, how much of the fiber is solubale/insoluble)…
so, i think im just going to not sweat this lil’ detail.
vroom, the reason why you only get 2 cals or whatever is because only some of it will get fermented to SCFAs and not because 2 cals/gram is the caloric content contained in SCFAs.
Another product of fermentation is gas. If you are “letting them rip” after a high fiber meal you can rest assured that at least some fermentation is taking place.
I had a good article on fiber that I will PM you if I can track it down.
The real problem with this whole discussion is that all you can do is talk in averages and no absolutes. This is due to many factors that have been mentioned such as fiber only getting partially fermented and different types of fiber getting fermented to varying degrees. Throw into the mix that the fiber from most sources will be mixed and you get a situation that is complicated to say the least.
In the end I say don’t worry about it. I usually subtract half the fiber I eat from my carb total and call it a day.
Thanks for the links. I think one part in there cleared things up pretty well for me.
It is estimated that in developed countries as much as 10% to 15% of ingested carbohydrate may be fermented in the colon
So, if I consume 30g of fiber, I’m looking at maybe 3-4g being coverted via fermentation and thus yielding up to 4-8 kcal? However, this as SCFA’s as opposed to carbs anyway.
This would be a good reason to use the net carb concept for natural foods if you are trying to estimate effects on blood sugar and insulin.