Making sense of weird numbers (not really, this time).

[Gryllotalpa]

To all the native English speakers here, could you please help me with the following questions (quite important in the calories count context):

1) What is the difference between "portion" and "serving"? To me, this seems to be synonymous, meaning the amount you eat in one sitting.

2) Any idea how the serving/portion size is estimated  in the available Fitbit calories tables?

Out of necessity, I am using the British tables since my German is not that good and there are no tables for my area. Here I have run into the following mystery while attempting an educated guess of calories  in a serving (about a tablespoon) of homemade sour cherry jam:

Two brands of sour cherry jam listed, both with about 244 calories per serving (good, means that homemade may be in a similar range). From available net data, these values, however, refer to 100 g of the jam,  so is this really supposed to be one serving? 

I suspect that some of the numbers in the tables may be more than a bit off.

[JohnnyRow · Accepted solution]

I have not used the food tracking so not sure this fits right, but I would say a serving is a fixed amount for that food, perhaps one slice of bread; but a portion is how much you eat at one time.  For instance maybe I make 2 full sandwiches using 4 slices of bread.  In that case, the portion would be 4 slices, equal to 4 servings but still my portion.  And your portion could vary at different times, but a serving is a set amount.

Or I could fill my plate with mashed potatoes.  The plateful is my portion, but it might amount to several "servings".

[Gryllotalpa]

Yes that would make sense - except that the serving sizes listed in the tables appear to be totally arbitrary and unrelated to what anyone could consider a portion. See my cherry jam example: the only way how to find out my actual consumption is googling up that jam' s calories per 100 g  and only then can I find out that serving in this case means 100 g. No idea if that jam' only comes in 100 g glasses. An even wilder example is butter, with calories per serving varying between 35 and 744, the later obviously being per 100 g..  Why can't serving size be listed as well?

[emili]

I am not sure I fully understand the question, but the jelly, butter or whatever you are eating should come with nutrition information on the label with serving size and calories spelled out. When I was logging food, I would actually work in reverse. I would look up what 1 gram/ounce of something was and then figure out how much of that I can eat. So for example.. 1 ounce of broccoli is 9 calories. I wanted no more than 50 calories of my dinner to be taken up by broccoli so I would eat 5 ounces of broccoli weighed on a scale. I would log all the items I ate often as my favorite food so I had the calculations available to me each time. Not sure if this helps, but here it is. 

[Gryllotalpa]

Well, that would assume that I am only eating food that comes with labels on it. I am definitely sure that I am not going to restrict my diet in this way. What I am missing iare more generic entries with values per weight or volume as opposed to per a  mysterious, company or country- specific serving. For example, try to look up milk in the tables  - you won' t find how many kcals are in 100 ml  of full fat or skimmed milk, only in a portion of Tesco milk!