Monday, July 13, 2009
Observations on Protein Intake in Low-Carbers
Last week I asked if people doing low-carb or zero-carb might be willing to test their blood glucose before and after meals and report their results. Many finger sticks later, we have a few tentative observations. Please note, this was NOT a scientific study in any way. Don't change your life or your eating habits based on what you read here. The purpose of this post is to consider ideas and to raise possibilities, particularly if you have been having trouble succeeding on low-carb or zero-carb. That said, here are the patterns that seemed to emerge from the data.
1. Some people, particularly people over 50, do have an increase in blood glucose following meals that are either entirely or mostly meat and fat. Dr. Bernstein says the optimum level of blood glucose is 83 mg/dl. For zero-carbers over 50, the fasting blood glucose was often somewhere between 95 and 110 mg/dl and could even go as high as the high teens. For long-time low-carbers over 50, fasting blood glucose was usually somewhere in the 80's. In both low-carbers and zero-carbers over 50, it was not unusual to have a 30-40 mg/dl rise in blood glucose after consuming a large amount of protein, such as a 12-ounce ribeye. Because protein is slowly digested, blood glucose levels sometimes stayed elevated for three to five hours or longer. It is important to remember that at blood sugars above about 100 mg/dl, insulin is secreted and its presence keeps fat in the fat cells. This may explain why low-carbers over 50 have such a hard time losing weight if they eat as much protein as they want. Insulin levels stay elevated for long periods, forcing most of what they eat into storage, and keeping it there until insulin levels finally come down again.
2. Most people under age 50 do not have a rise in blood glucose following a meal, even a large meal, that is mostly meat and fat. I had three participants in the under-50 group whose blood sugars stayed approximately in the 80's following meals ranging from a 1/3 pound hamburger to a ribeye steak. Two of them told me that they occasionally see rises to near 100 mg/dl, but often there is no rise at all.
3. Decreasing protein intake in two participants over 50 to the amount recommended at Blood Sugar 101 caused a decline in average pre-meal blood glucose to the low 90's and post-meal glucose values between about 90 and 110 mg/dl. In fact, both of them started losing weight again after several months of eating as much protein as they wanted and gradually gaining weight.
4. And then there were the outliers, which I shall address below.
Two participants occasionally experienced a fall in blood glucose following a low-carb meal. Neither has been diagnosed with diabetes. Nevertheless (unless they were eating more carbs than usual), their blood glucose sometimes declined after they had eaten a low-carb meal of meat and vegetables. One was a man and one was a woman. One was under 40 and one was over 60. The woman, SC, suggested to me that it might have something to do with the fact that she is a super-taster. When I checked with the other one, who happens to be Jimmy Moore, it turned out that he is also a super-taster. Just to be sure, I checked with super-taster Cleochatra. She did not have blood glucose data to give me, but she said, "I can tell when I've eaten a carrot, even when it's been hidden in a dish, because my stomach is growling within minutes and I want to dive face first into various vats of puddings. I can say in all honesty, artificial sweeteners made me starve...and when I'm VLc I feel fantastic. No woobly or feelings of hunger at all." Later she specified that Splenda and the sugar alcohols are the artificial sweeteners that affect her.
[In the comments, Mariasol asked what made a person a super-taster. Although there are tests for this ability, I simply used an informal question as a criterion: If I poured out five unlabeled dixie cups of Diet Rite, Diet Pepsi, Diet Coke, Coke Zero and Splenda Coke, could you correctly label each cup with the brand, based on taste alone? If your answer to that question is yes, you probably are a super-taster. Subsequently, I have been told that when a super-tasters are cooking something and then add in the salt, they can smell the salt. Just like everything else in this post, the super-taster information has been collected in a non-rigorous manner, so please do not take it as settled science.]
From a limited sample size of three, I can speculate that super-tasters are the ones whose insulin is on a hair-trigger. As soon as they eat, or maybe even before they eat, they secrete enough insulin to nail any food that might appear in the stomach. And if that food happens to be diet soda, it's possible that the insulin secretion occurs anyway. This can either trigger hunger pangs, or if the diet soda is consumed continuously, can keep insulin levels relatively high and thus prevent fat mobilization and weight loss.
All of this is anecdotal. It didn't come down on tablets at Mt. Sinai, so various parts of it could be wrong. But I present it as something worth thinking about in the context of a low-carb lifestyle.
Very many thanks to Cleochatra, ES, D, Jimmy Moore, K, KM, LR, SC, SG, SO, V, VS, P and U for providing data that was used in this blogpost.