I was reading a book called Formula 101, by Gene Daoust. He explains on page 224 that in a protein food the amount of protein absorbed depends not only on the fiber content of the food, but also on what is called the "rate-limiting amino acid" of the food. He describes that all the amino acids in a food must be present in the right balance for the body to use the protein fully. If the protein is low in just one amino acid, your body can use only the amount of the lowest amino acid found in that food. He goes on the give the example of black beans, which are low in the amino acid, methionine. They have a usable protein score of only 50%. Tofu, also due to low methionine, has a score of 43 percent. Cottage cheese has a rate-limiting score of 93%. Taking the above into consideration would greatly alter many of our zone block calculations, especially when considering vegetarian sources of protein like the beans and tofu. Although Dr Sears recommends to not count the protein in beans( I do, though, because I eat a lot of them), he does advocate counting the protein in tofu and soy products and recommends that we eat good quantities of them. Therefore, at least for me, this question is an important one. Does Newbie or Sue or anyone else have any input on the above? To my knowledge Dr Sears has not written about it. Thanks.

Steve, that is interesting information. I have not seen Sears write specifically about this, either. I know that he speaks of veggie proteins as proteins that are not completely absorbed, and that we don't count those proteins. But, he focuses more on the fiber content of the food as rationale for the poor absorption of the protein.

I would also be interested in hearing more about this. From personal experience, I have not had good luck in using soy products for protein, as I don't get adequate satiety when I use this protein. The "rate-limiting amino acid" idea may be a factor.

Thanks for your reply, Cranberry Cat. I just called a Zone Proffessional and she couldn't answer the questions. She referred me to Dave, who woks with Dr Sears, and I left a detailed message on his machine. When I get his reply I will write again.

Regarding my question above, I was referred by a Zone Professional to Dave Schreck, who works closely with Dr Sears. Dave was very obliging and explained that the "rate-limiting amino acid" phenomena I mentioned in my question above was indeed true but that Dr Sears chose not to explain it in his books so that we could keep our calculations simple and still be basically accurate. So it depends on how exact one wants to be. For me, the numbers I listed above are important because I eat a significant quantity of beans and tofu a day. For others it might not matter very much, especially taking into consideration one's overall daily consumption plus the lack of necessity for many zoner's to add up every single gram. How does that jive with you, Cranberrycat?

Hi steve!

It brings to mind some outdated info about protein from vegetable sources. You might be aware that it was once thought that vegetarians needed to eat certain foods together to provide the full complement of the necessary amino acids (I think it's 10 specific amino acids) to be able to use the protein (e.g. eating rice with certain beans), but that has since been dispelled when it was found that the body has pooled amino acids from other meals that are available to fill in for the missing amino acids. I'm not absolutely sure, but this may be a factor which enables one to get more protein than you may think you are getting if looking at only the individual foods.

Incidentally, my experience with soy protein has been the opposite of Cranberry's. I get better Zone results from soy protein based meals than I do from other low fat Zone proteins (e.g. meat, fish, poultry, egg white). Just goes to show how individuals differ!

Again, I think this is very interesting! It makes perfect sense to me, seems to explain why I don't get good meal responses using tofu for protein, because my protein/carb ratio must be altered with this combination. And, on the other hand, when I toss beans into a meal, I am counting it as carb, but it must be giving me SOME protein, and so this also may be altering the protein/carb ratio and giving me slightly better meal responses.

In any case, sounds like if you eat a significant quantity, you might actually get some absorbable protein. But, the challenge would be to figure out how much you are really getting!

Thanks for your replies, ladies. Actually, regarding protein that is floating around from previous meals and making up for the missing aminos in another protein, Dave did mention that point to me in order to demonstrate that it is not that simple to measure the absorption of any given protein. Although I tend to like everything to be precisely defined, the bottom line for me on this one is that the zone works great for me (25 pounds in three months) with or without a few more or less grams of protein counted in, so unless I hear anything more conclusive I will do some kind of estimate when doing my calculations and be satisfied.

By the way, because I eat a lot of veggies, and they all have protein, the grams add up quite a bit. I always take off 30% or so of the total due to the fiber factor. Do you do the same, or do you work it another way, like by not even including the protein in the veggie, as I have heard that some do? Spinach, for example, has a lot more protein than carbs, and other veggies have more or less equal amounts of protein and carbs, so it seems pretty significant to me to include it. Another point of confusion to throw into the mix is that different food charts give different values for the same food. I just deal with that by taking the average. One reason different values are given is because the same food grown under different circumstances does indeed have a different nutritional value than another. I guess there is no substitute for using our intelligence to fine tune our individual program so that it works for us given all the different variables that invariably come up.

I am eager to hear your comments on the above.

Steve

You're welcome Steve!

Here's another bit of info. You're not absorbing all the protein that's in every veggie you eat. Barry has explained that not all the protein in plant foods is available for absorption in the human digestive system because some of it is bound in insoluble fiber. We don't digest insoluble fiber, so the protein trapped in it is basically excreted and never absorbed. Soy is an exception, with much of the protein it contains being usable.

I agree with you about there being no substitute for individual fine tuning. Even if it were feasible to precisely count every last little gram of each macronutrient, there would still be the need to fine tune, since the starting point P/C ratio of the Zone diet is not the ratio that's appropriate all.