What is a "serving size"?

I posted this question to another forum but I think I may get a better answer here.  This sounds silly but what is a "serving size" to us?  I am a vegetarian so most of the protein sources I eat are not on the list of proteins my nutritionist gave me and I'm trying to figure out how much I should consider a "serving" when using the food exchanges on my meal plan.  Like for example my MD's office considers 1/4 cup of canned Salmon to be equal to one protein.  But how would that logic work if I were trying to figure out a more unusual vegetarian food like say for example tempeh, seitan, soy dogs, soy burgers, or any arbitrary food I would usually eat for protein.  I guess what I'm looking for is like a formula, like if X amount of the food has X grams of protein and less than X calories and X amount of fat it would therefore be equal one protein exchange.  Sorry for being so long winded but this is starting to screw me up and I don't think I'm eating the right amounts. 

It varies by food, but here are some generalities Serving size is a "typical" amount consumed at one time.  Great, now you've had WLS and your capacity is totally altered and "typical" may not be so for you. A serving of protein (meat) is usually 3 oz and provides approximately 21 g protein. This is not the same as an "exchange" which would be a one ounce serving (you usually get 3-5 "exchanges" to spend at each meal).  Use the food label. If you are looking at a food label, it tells you what constitutes a serving.  You can look at your portion and compare it to a serving (on the label) to get your calories/protein contribution. One Boca burger is a serving - it has 110 calories & 14 g protein  If you are comparing your vegetarian foods to meat - you need a higher quantity to meet your protein needs.  You probably need to move away from a pre-planned menu and sort of "free-style" it to meet your daily calorie & protein goals.  Use one of the on-line trackers to calculate your intake - adjust up or down to meet your goals. Does this help?

Thanks Danielle, I have never used an on-line tracker before, that really helps!  I guess I was just so concerned about eating exactly as they told me I was afraid to "free-style", but as long as I get my protein needs met and don't go over the calories I'm supposed to have, it probably doesn't matter.  I think my RD was thrown by my not eating meat, eggs and dairy.  She didn't have much info for me regarding the veg lifestyle and gastric bypass.  I'm trying to find a RD in my area that is familiar with vegetarians AND gastric bypass but so far no such luck.  You don't happen to know of anyone in Maryland who might be able to help me, or how to find such a person?  Thanks again for your response! ~Bonnie

You have to buy all those alternative protein sources, right?  So on the package they come in, there should be a nutrition label, just like other foods.  If all else fails, you could always check any one of the online calorie tracking websites (I use www.fitday.com).  I personally don't think that a "serving size" is necessarily different for WLS folks than it is for normal folks.  It just depends upon how much of that serving you can eat.  A 1 cup serving size might be too big of a portion for you, so you'll only eat 1/2 cup.  Then just divide all the nutrition information on the label in half.   When food manufacturers put the nutritional label on food, they have to base that info on a certain amount of food - serving size - so it can be easily understood.  That doesn't mean you have to eat only that amount for the nutrition to apply to you.  Just do the math to figure out what you actually ate. I'm a bit confused about your comment regarding "1/4c canned salmon equals 1 protein."  Are you counting how many grams of protein or some other altered version.  According to FitDay, 1/4c of salmon contains 7.5 grams of protein.   A 1/4c of tempeh contains 7.69 grams of protein. (just for comparison sake.) If your surgeon's office is doing some alternative type of protein counting, then ask them to translate that formula into actual "Grams" ---- which is the universal way of reading labels.  (That's on of the things that bugs me about Weigh****chers.) Hope this helps, Pam

Thanks Pam, that www.fitday.com really helps!  Yeah my MD's office is a bit confusing, they assigned a meal plan with lists of arbitrary amounts of foods saying that each amount equals "one protein exchange" and that I can have a certain number of exchanges for each meal.  However the list doesn't do me any good since I don't eat those foods  and to try to explain it to my RD only gets the "what's wrong with eggs and dairy products, why can't you eat those?" argument from her.  But I think you have a good idea about just asking for universal way of doing it, because her exchanges just don't allow for new foods.  I guess I'm so preoccupied with eating exactly as they tell me to I'm afraid to read labels and do my own math so maybe if she gives me some kind of guidelines I can figure out my own meal plan.  Thanks again! ~Bonnie