Community Discussion Forum Parent support Weighing Foods

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    Avatar of Rachel

    I am a little confused about weighing foods. In the low protein food list they have a standard weight and then the mg of phe per gm of food. But what if the food item does not weigh the same as what is listed in the book? Do you still use what they they give you to weigh? Say I have a fresh, peeled, medium banana in the book the weight is 114gm but what if the banana weighs 125gm, do you will use what is in the book to measure with(mg of phe per gm of food)? I am just a confused mom haha.

    God Bless

    Avatar of Janice

    Well my daughter is now 6 and I have a 2 year old too with CPKU, and I usually estimate it I would consider that to be 1.1 exchanges or 16mg  (assuming what you said was 114 gm was 15 mg)   but basically I would know that if 15 mg where 114 then 171 gm would be 22.5 mg   or   142.5  would be 19 exchanges and so on and so on

     Okay that was really confusing even for me and I was doing it.   I will say that over  time you learn these things There are certain things (their favorites) that I dont even have to think about I just know how much they are.  But for now it is alot of math but keep a c alculator handy and you take the gram and and mg and keep divideing them like how I got the first answer was

    114 mg is the whole banana  and it is 11 mg over you take the 114 divide it in half that is 7.5 mg  and 57 gm 

     then you divide it in 1/2 again  

    57  divided in half is  28.5   which is 7.5 mg divided in 1/2 too  =  3.75 mg

    divide again


    28.5 divide by 2 is  14.25                      

    and then 3.75 mg  comes to 1.875

    so there is probable an easier way but i was never any good at math so I this is as good as it is for me, luckily I do have a good memory so I was able to eventually memorize most of the common things they eat. 

    Hope this helped a little and didnt confuse you horrible.

    Avatar of Sarah

    Example: The book says a banana weighing 115 grams is 40 mg of phe.

    Divide 40 by 115.  This equals approximately 0.35.  Each gram of banana is 0.35 phe. You can multiply any banana weight (in grams) by 0.35 to figure out how many phe's.


    Avatar of Rachel

    okay so no matter how much the food actually weighs the MG of PHE per GM of Food is always the same, it doesn't change if the weight of the food changes.

    God Bless


    Avatar of

    If you are weighing foods, use the mg of phe per gram of food this is the most accurate, as someone else said, this never changes (unless a products ingredients change).

    For example,

    Weigh the banana.  Let's say it is 115 grams.

    Take the banana weight and multiply by the mg of phe per gram of food to get the phe in the banana.

    115 g of banana X .35 mg/g = ~40 mg of phe in the banana.

    We have found large discrepencies in many foods between the listed weight for a serving versus what something you have may actually weigh.  No two portions of food are exactly the same.  We no longer estimate and always weigh our son's food.

    take care.

    Avatar of Eugene

    I am working on an applcation for the PC to do all these calculations automatically for you. You can check out my group on facebook by searching for PKU Tools.


    Avatar of Breanna

    The mg of phe in each gram of food is always the same. A very simple way of figuring out how much phe is in any food item is to take the weight of the food in grams and multiply it by the number in the Mg Phe/Gm food column in the phe book.

    For example if you have a banana that weighs 140 g it will obviously be a bit higher in phe than a standard 114 g banana. Since each gram of banana contains 0.38 mg of phe you multiply 140 by 0.38 to give you 53 mg of phe for that banana. In the same sense if you have a smaller banana that weighs 100 g you would multiply that by 0.38 and that banana would have 38 mg of phe.

    I hope this helps!

    ~Breanna Hardy 18 CPKU

    Avatar of Rachel

    Thank you all so much for your help. We have been counting mg of phe instead of exchanges for a couple of weeks now and I believe I am getting the hang of it, I actually like it better than couting exchanges. I also made my first loaf of low-pro bread and it turned out great! My son loved it too. Thank you again for you help!

Viewing 8 posts - 1 through 8 (of 8 total)
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