Sunday, July 5, 2009

Protein Intake and Blood Glucose Levels

Low-carbers know that when a person eats foods that contain carbohydrates, his blood glucose will rise. As the pancreas releases insulin in response, the blood glucose levels will gradually return to normal.

What happens when a person eats protein? Insulin is released in response to protein as well, enabling the amino acids to be removed from the blood and stored in the tissue. The cells don't know the insulin is there to remove amino acids from the blood, so they will take up glucose from the blood as well. To prevent hypoglycemia, the liver gradually releases glucose into the blood to replace the glucose that has been stored.

In the graph above, the white lines show us that when a normal person eats 50 grams of protein, the blood glucose remains the same out to five hours after the meal, even though a significant amount of insulin has been released. The person with type 2 diabetes is represented by the yellow lines. His blood glucose levels start out at a much higher level, but when he eats 50 grams of protein, his blood glucose levels also stay steady out to two hours and then actually begin to drop because a great deal of insulin has been released. These graphs are found at Metabolic response of people with type 2 diabetes to a high protein diet.

It is important to realize that the response to protein in both the diabetic and non-diabetic person are happening in people who are not low-carb-adapted. Low-carbohydrate-adapted people are able to make all the carbs they need through gluconeogenesis. Their brains and muscles have switched over to the use of ketones and fatty acids for fuel, and the 40 or so grams of glucose they need for glucose-requiring tissues are readily converted from glycogenic amino acids and the glycerol backbones of triglycerides. So, what happens when a person who eats very low carbs has a meal of protein? For a rather extreme example, look at the graph below.

Lex Rooker is a very dedicated and meticulous individual who posts at the Raw Paleo Forum. (In no way do I either support or condemn what Lex does regarding his diet, but his journal certainly makes fascinating reading.) For about two years, Lex ate a single daily meal in the afternoon, at the time marked by an asterisk on the graph. This meal contained 150 grams of protein and consisted of 68% fatand 32% protein. As you can see, his blood glucose remained rock-steady at about 106 mg/dl throughout the day. But a couple of hours before he ate, it would drop to 95 mg/dl. After he ate a meal consisting solely of meat and fat, his blood glucose would rise about 25 mg/dl, returning to baseline in about four hours. (The graph shows a rise of 15 mg/dl, but he refers to the amount of the rise several times, so this may be an error in the graph.)

At one point Lex decided to switch things up a bit. He kept his calories the same, but ate only 90 grams of protein per day, making the ratio 80% fat and 20% protein. His baseline blood glucose dropped into a range between 68 and 78. After his single daily meal of meat and fat, his blood glucose would rise about 15 mg/dl, though it would take longer than before to come down to baseline. It appears that decreasing the amount of protein intake also decreases the amount of glucose released into the blood of a low-carb-adapted person.

People who are not low-carb-adapted do not do much gluconeogenesis because they get plenty of glucose from their diet. People like Lex Rooker who eat no carbs at all, apparently do quit a bit of gluconeogenesis. Low-carbers fall somewhere in between those two points. This provokes a question to which I do not currently have an answer: What does a normal blood glucose curve look like in a low-carber? If he chooses to eat only meat and fat at a particular meal, does his blood glucose rise or does it stay steady? If he eats a few carbs with each meal, does it rise less, or does it rise more than it would without the carbs?

In other words, this time it's not a blog, it's a bleg. If anybody has data on what a normal (or abnormal) daily blood glucose curve looks like in a low-carber, would you please share that information in the comments? Thanks!

(If any of the graphs are too fuzzy to read, just click on them and you'll get a clearer version.)

22 comments: said...

I just discovered your blog via a link from another blog. I love the technical details here, and especially the graphs. I have Type 2 diabetes, and I check my blood glucose up to 10 times a day, but I may start keeping graphs too. Fascinating stuff!

pooti said...

Hi Stargazey. Nice post.

Dr. Bernstein says that blood sugar is affected by protein at about 2mg/dl for every ounce of lean protein consumed. He says fat does not impact blood sugar at all. He predicts that 5g of carbs will cause about a 10mg/dl spike, depending on the person. (I'm pretty sure these numbers are in reference to metabolically injured people.)

I can say, these numbers are pretty true for me as well. One of the things fat does for me is that it delays (slows) stomach emptying so my spike lasts longer and is generally not as high as if I ate carbs.

Also, Peter at Hyperlipid blog writes great stuff and has discussed the effects of long term ketogenic diets on blood sugars. In general, blood sugar tends to rise in the fasting state to somewhere around 100, for people following a ketogenic diet. I have also seen this to be the case with me.

BTW - there is nothing "wrong" with JMs blood sugars. They all look remarkably normal to me - not even in the pre-diabetic or reactive hypoglycemic area. I would bet Bernstein would say the same.

Stargazey said...

Pooti, as you suspect, it's Jimmy Moore's blood sugars that prompted this bleg. On 7/2/09, his blood glucose fell nine mg/dl afer his first meal of the day. On 7/3/09 it fell 23 mg/dl. If he is low-carb adapted (and after 5.5 years on low-carb he should be), why would his blood glucose decline at two hours?

I'm not saying we should get Jimmy to the emergency room, but when the subject came up, I realized that I don't know what "normal" means for blood glucose in a low-carber who doesn't also have type 1 diabetes like Dr. Bernstein.

Stargazey said...

Hey, Jim, welcome to the blog. If you are low-carbing and start keeping graphs, I'd be very interested in seeing them.

Anne H said...

I have asked myself these same questions many times. Pooti - I'm glad to see you, and remember you from before. Stargazey, you must be a Medical person. You seem to be very informed and precise! I love your blog.

OnPoint said...

Stargazey, the questions you posed here have always been the core ones for me - well, relative to my limited understanding of such things. I am particularly interested to find out the difference is blood glucose readings between fat/protein only and fat/protein w/ a few carbs. If the glucose rise were to be about the same in both cases, what would that mean?

pooti said...

My suspicion is that it falls because of the fat content of the meal and the delayed stomach emptying it elicits. Just a guess is all...

Stargazey said...

anne h,

Would-you-believe I have Ph.D. in medical biochemistry? My dissertation was actually on insulin signaling, but I haven't done any biochemistry in well over a decade. This blog is a small attempt to get that section of my brain up and running once more. :-)

JD said...

I hope you post this information over at JM's menu site. He keeps saying that excess protein converts to glucose. From the evidence you have here (I am excluding Lex's results) this is a fallacy for the average person. Dr. Eades says that protein is only converted when necessary. Your info seems to bear this out.

Stargazey said...

That's "a" Ph.D. Obviously my brain is not up and running yet today.

Pooti--good question. But Lex Rooker was eating 68% fat and then 80% fat, which is much more than JM does. Yet Lex's blood glucose still went up after eating a meat and fat meal.

pooti said...

Stargazey, I am a T2 diabetic. When I was trying to ZC (I did eat dairy and eggs) along with meat and fat, my blood sugars rose very high. Higher than when I eat a smaller amount of protein with low carb veggies (daily carb total 20 or less). I could also feel my insulin surging and the resulting cortisol dump. I felt really awful on it after about the first 10 days. Also, I had much more hunger and wanted to eat more at a sitting - another signal that insulin was surging. My blood sugars would go up 20-30points after a zc meal and my fasting sugars were back into the high teens when I quit zc.

JD said...

As to Lex's results, perhaps he is converting a fair amount of protein to glucose. As he only eats once a day I guess that makes sense. Replenishing his glycogen stores? The only issue with Lex is that n=1. Interesting but not scientifically valid.

I wonder if Phinney who has down low carb/zero carb(?)studies with bikers has any results regarding blood sugar and insulin.

Stargazey said...

Pooti, if you don't mind telling us--what are your pre-meal and 2-hour post-meal blood glucose values now that you're back on low-carb? What meds do you take for the type 2?

Just to keep my tally current: you are now the third person (besides Lex Rooker) who has reported significantly higher blood sugars following a meal of fat and meat on zero carb. One was non-diabetic, one was possibly pre-diabetic and you are type 2 diabetic.

pooti said...

Stargazey, I'm in and out of pocket right now. My mom is dying and we are taking shifts caring for her. When I can think straight again, I will give do a two day experiment with numbers for you. One day will be all zc, the other day will be low carb 20g carbs.

I don't take any meds. I've been low carbing for many years. I was to have gone to my doc in June but then the crisis with Mom came. I haven't rescheduled yet.

Stargazey said...

I'm sorry, Pooti. Our prayers are with you and your mom.

Jade said...

My best wishes to you, dear pooti.

OnPoint said...

Pooti, so sorry to hear about the downward turn in your mother's condition.

OnPoint said...


I'm posting this here b/c I do not feel like battling Didirina.

You should post whatever conclusions you draw from your debate with Didirina here. Didirina makes an excellent case, but I'm still not totally convinced. You'll see why as you read further.

I think you did a very nice thing to offer Jimmy the meter and strips. It helped add some relevance back to his blog. I fully understand his perspective, but I also think that considering his stature, it makes sense to show the real impacts of his menus. Inadvertently, you laid a trap for Jimmy.

Or, am I looking at this wrongly?

Let me explain.

Didirina and Jimmy are now apparently winning the debate about diet sodas. Jimmy is showing purple on his ketosticks after eating FOUR SLICES OF BREAD AT ONE SITTING LATE AT NIGHT. Jimmy is steadily proving the validity of his diet as it relates to LC.

But why is he back up to 260 lbs - er, 83% - er, whatever the mystery number is? Sweet-free worked, but why it worked is now more unclear than ever. Jimmy will have even less incentive to make any adjustments to his diet now that he is justifying his WOE.

Again, we have NO idea why Jimmy is gaining weight, nor do we know why sweet-free worked. I guess Jimmy's doomed to gain several lbs a month of "mysterious weight gain."

It's just all one big mystery!

Stargazey said...

I appreciate your thoughtful and insightful comments, OnPoint.

When I suggested the glucose testing, I suspected that while doing the testing JM would start to eat a more conventional LC diet and he has. Now that he is reintroducing products, it would be nice if he did hourly blood glucose and checked his ketones as well to see what effect each product has on his health. It may be that the Julian bread is nothing more than fancy-looking fiber, but we don't know that until somebody actually measures glucose and ketones after eating it. And if Julian bread is okay, it doesn't mean by extenstion that the garlic bread is okay.

As far as the Splenda issue. I have to go where the data takes me. The first study suggested that sucralose might raise insulin secretion because it interacts with sweet receptors in the gut. In Jimmy's specific case, this makes sense. However, the second two studies showed that in normal humans in well-controlled conditions, sucralose in the gut does not cause insulin secretion. Unless there is some aspect of these studies that I'm missing, eating Splenda is probably not going to lower blood glucose in most people.

HOWEVER, Jimmy might be an outlier. He may have something special going on in his genes that causes him to gain weight when he eats artificial sweeteners. But unless he does some sort of Splenda tolerance test and has continuous monitoring of his blood glucose and blood insulin measured in a lab, I can't say that for sure.

curious1 said...

Thank you Stargazey, for a terrifically informative site. I have been researhing, as a low-carber, the effects of insulin on aging and fat storage, and you have answered so many questions in just one sitting. Thank you for sharing your vast knowledge, education and insight! I look forward to learning more. You really should put this into a book, (because this is the book I would like to write but it would take decades to get the PhD). Thanks.

DHG said...

From OnPoint: "But why is he back up to 260 lbs - er, 83% - er, whatever the mystery number is? Sweet-free worked, but why it worked is now more unclear than ever. Jimmy will have even less incentive to make any adjustments to his diet now that he is justifying his WOE.

Again, we have NO idea why Jimmy is gaining weight, nor do we know why sweet-free worked. I guess Jimmy's doomed to gain several lbs a month of "mysterious weight gain."

A little over one year later, and the same is true. He's still gaining/losing/gaining/losing with a net gain. No diet sodas for months, relatively sweet-free, yet no significant weight loss. Someone brought up dairy, but he's nervous about that. He does eat what seems to me to be a LOT of cheese, and when he was gaining a couple of years ago he was eating all sorts of desserts made with cream cheese, heavy cream, etc. And then there's the LC ice cream. Maybe...

Stargazey said...

Hi, DHG! I was just thinking about Jimmy Moore's blogging practices yesterday. And here you are today, making a comment.

One of the things I learned last summer was that Jimmy does not necessarily tell the truth about things. About the quantity he eats (a person at a meet-up looked at what Jimmy reported he ate and said it was much more than that). About where he eats it (some of his "home made" meals are pictured on plates from various restaurants, and bear a suspicious resemblance to menus at those restaurants). And we all know about the blog comment he changed from negative to positive, until the commenter exposed him doing that.

What I'm saying is that what Jimmy reports may not be a complete and accurate accounting of what he actually eats. He may be indulging in a few dinner rolls at restaurants. His single serving of a low-carb dessert may be six servings. The calories add up, and if you're not doing pure low-carb, so does the body fat. If you are pre-diabetic, you simply can't eat fat and carbs together and get away with it. Your body counts the nutrients even if you don't.

I could be wrong. All I have is about four examples of instances where Jimmy shaded the truth. But it's something to think about.