Carbohydrates with high glycemic indecies enter the blood stream quickly, causing a spike in blood sugar and a subsequent spike in insulin levels.

As protein stimulates the release of glucagon, would a liquid form of protein cause the liver to release larger amounts of glucagon than would a solid form (which enters the blood at a much slower rate).

Simply put, is there an "index of protein absorption speed"? Does the speed of protein absorption even matter?

Thanks,
Michael N.

Good question!

I don't believe that I have ever read about it. I DO know that some proteins work better for me than others, but I honestly could not tell you why that is.

Good question, Michael! I'd really like to know the answer to that especially since I'm about to invest in a good blender to make protein shakes. Sue, do you know the answer?

Happy Zoning!
Karen

There's no index that I'm aware of. Speed of absorption does matter, but all proteins require more energy to break down than carbs. I know that Whey proteins are considered fast, Casein proteins slow, and egg somewhere in between (but is considered the ideal because it supplies the essential amino acids). For more information on this I suggest looking for information regarding body building - the protein masters.

Personally I mix my proteins. My morning meal (if oatmeal) I have a mixture of Casein and Whey, approximate 60-75% Whey to Casein. The reason being I'm 'breaking the fast' but I also want the slower digesting Casein to hold me over till my next meal. Of course if I'm having egg whites in the morning there's no need for additional protein. The same for lunch if additional protein is required. Dinner rarely requires additional protein. If I have a late snack or meal I prefer the Casein.

Approximately 80% of dairy is Casein. That's why low-fat cottage cheese is often (not sure about the Zone, I'm new) recommend for a late night snack.

Welcome to the Zone, James! I hope you enjoy it as much as I do. Are you a body builder by any chance? Thank you so much for this information. I will be better informed when it comes time for me to buy my protein powder.

Happy Zoning!
Karen

Hi!

I don't know if a protein absorption speed index exists.

All protein increases insulin levels. One of the reasons Barry Sears favors soy protein is that it has less of an effect on insulin than amimal protein. He considers beef and pork, with the exception of tenderloin, to be low quality protein for the Zone because of the amount of saturated and omega 6 fat they contain. Dr. Sears Zone Protein Powder is a exceptional blend of high quality protein that dissolves quickly and is absorbed slowly by the body.

Hmmm, I thought that protein had a very small effect on insulin levels? Don't think I would have considered that. Interesting that soy has less effect on insulin than animal protein, because soy naturally has carb in it. And, for me personally, when I use soy sources for protein, I generally have less satiety with meals/snacks (obviously taking into consideration that the P/C ratio may be tipped a bit more).

Michael's post seems to be asking more about whether certain proteins stimulate glucagon faster, rather than discussing insulin.

<div class='NTForums_Quote'>Posted By Karen on 01/10/2009 8:36 AM
Are you a body builder by any chance?
</div>

No but I've done a bit of research, for my own health and exercise program, in this area. I've read that Whey protein can be completely metabolized in 2-4 hours, while Casein 7+. Of course the internet is a great resource but the signal to noise is low. So while one resource states eggs metabolize slower than whey but faster than Casein another states the opposite.

Today I found this link which looks excellent. All articles appear to be up to date and research based. Best of all the presentation is easily digestible (ha!).

http://www.bodyrecomposition.com/ca...on/protein

My take away from the Zone (thus far, 2-3 weeks in) is one of balance based upon determining your daily protein requirement. Protein is spread throughout the day and balanced with appropriate carbs and fats to govern insulin response (among other hormones). Because the body can only metabolize so much nutrients over given period it's important each meal is appropriately sized and composed. The Zone is multifaceted balance.

Wow, good information, James!

I will have to follow this link and do some more exploring.

Off the top of your head, do you know how quickly soy protein metabolizes?

Oh, just peeked at that link. Looks like I will need much more time to "digest" this!

Thanks for the information, James! I will look at the website a little later, when I have more time. Thanks, again!

Happy Zoning!
Karen

<div class='NTForums_Quote'>Posted By Cranberrycat on 01/10/2009 6:25 PM
Off the top of your head, do you know how quickly soy protein metabolizes?
</div>

Not of the top of my head, but in "What Are Good Sources of Protein? - Speed of Digestion Part 2" near the bottom Lyle presents a table that according to it Soy is digested at the rate of 3.9g/hr. That same table states egg are among the slowest digesting rate although measurements were obtained indirectly. This is the first time I've actually seen a presentation with measured results and I find some of the results dubious. Everything I've read about egg protein up till this stated it digest faster than Casein but slower than Whey.

Just noticed the comments at the end of the article. Other people have questioned the presented test results and there Lyle ("admin") states that's all the date available. In some instances, such as Soy, the source (powder isolate/tofu/beans/etc...) wasn't mentioned. As we already know the processing necessary to extract nutrients affects the metabolism rate. This is, apparently, why Dr Sears doesn't count proteins found in vegetables; those proteins may be unaccessible due to being encased in a cellulose matrix.

One more point about the data presented. Lyle states that most studies are performed under conditions that do not mimic standard diets, i.e. the purpose is to isolate the effects of protein within the target group(s).

Thanks for expanding on that!

I think it is interesting stuff, something that I am definitely not very knowledgeable about, but maybe it will explain why some meals work better than others when all I did was change the protein.