I received a letter from a fellow physician asking me if he thought people who had stalled in their weight loss on Zero Carb (meat only diet) needed to limit protein intake and why. Here is my response. It's has more scientific language than most of my posts but I know many of you are quite scientifically literate though other may prefer the story in the laymen's language of THIS POST.
I was so glad to get a question from a fellow physician. Even retired I remember how busy I was in practice and raising 3 children, especially the years I did both office and hospital care, something they don't do in Europe and even in the US the practice is fading I understand. I know how precious your time is, especially if you are still raising children so I will try to waste no more of it. The short answer is that I feel people who have abused their bodies for years with carbohydrate with fructose containing carbohydrates like sucrose being the most toxic carbohydrates because of the toxicity of fructose to the liver and it's 8 times higher affinity to cause non-enzymatic irreversible binding to proteins than glucose to be far less tolerant of high protein levels than people who have not. And there are some people who have severe insulin resistance just based on their genetic make up who also are unable to tolerate high protein loads. I feel that in these people due to insulin resistance much of the excess protein is turned into sugars which are not handled well by the body due to insulin resistance and thus to achieve health and weight loss these folks must limit protein intake as well as carbohydrate intake to avoid high Glycosolated Hemoglobin levels (Hemoglobin A1c levels) and mesenteric fat deposition which we know is such a bad risk factor for heart disease and that any weight loss can be halted if they do not. And I feel that to lose the toxic mesenteric fat the best technique is probably intermittent fasting because of it's ability to allow insulin levels to fall very low. Having said all that, let me share with you some of the scientific evidence that led me to this conclusion.
Depending on whose statistics you believe, insulin resistance is quite common . The NHANES study reported a prevalence of 34% for the metabolic syndrome in the US which of course is triggered by insulin resistance. Dr. Joseph R. Kraft, a British Pathologist who did over 10,000 insulin tolerance tests over his many years of practice felt the incidence of insulin resistance was much higher and documented it could also occur in people who were not fat. Here is a nice interview with Dr. Kraft where he explains his work.
There is also good evidence that persistently elevated levels of blood sugar over years can cause the insulin producing beta cells of the pancreas to first lose the ability to put out the initial short burst or spike of insulin that is the normal physiologic response to a carbohydrate containing meal and this is of course important because this spike is the signal that triggers the liver to shut down sugar production by gluconeogenesis and glycogenolysis. And with persistent glucose elevation can also cause the apotosis (death) of beta cells which cannot be replaced. Here is an article about that.
Another factor that I think is involved is loss of insulin sinsitivity by the liver due to Non-Alcoholic Steatohepatitis (NASH) which is epidemic in the US and closely linked to insulin resistance. ARTICLE
Of course as any physiology text will tell you the body releases insulin in response to both the ingestion of carbohydrates and protein. I think most NASH is caused by carbohydrate consumption, especially Fructose containing carbohydrates like sucrose (table sugar) because Fructose can only be metabolized through the same pathways in the liver as Ethanol and almost all of it is converted to fatty acids and eventually triglycerides that tend to be deposited intrahepatically. The Pediatric Endocrinologist, Dr. Robert Lustig describes this in detail in his wonderful lecture "Sugar, the Bitter Truth" which has been viewed more than 6 1/2 million times.
I believe that the combination of the damage to the pancreas and the damage to the liver caused by excess carbohydrate, especially Sucrose and even worse, high fructose corn syrup intake eventually combine to make the insulin resistance so severe that in order to lose weight and avoid the mesenteric fat accumulation that can happen, even in a person who appears phenotypically thin and is so strongly associated with coronary artery disease, a person who has metabolically damaged his liver and pancreas must limit protein intake. I also feel intermittent fasting is so important because it allows insulin levels to drop very low and even a small amount of insulin can block the adiposcyte's ability to perform lipolysis and thus be able to release fat to be burned. I have explained this many times in laymen's language but it felt good to speak doctor to doctor. I plan to publish this as web page in my blog, but let me reassure you that I will not include your name, email or even your location, ever! It is my hope that we might someday enjoy the collegial discussion of ideas like those I remember from "Journal Club" when I was in residency rather than the strident, name calling, intolerant dialogues I now see going on, especially in the nutrition, diabetes treatment and coronary artery disease prevention arenas where I fear the influence of drug companies eager to reap profits for stockholders and the entrenched researchers and Journal Peer Reviewers, almost totally dependent on drug company and government largess for funding combine to create a rather toxic environment for true scienctific discussion to occur. ps. I'm 1.85 meter tall and currently weigh and weigh 80.5 kg. I was stuck at 98 kilos for several months before I began intermittent fasting and limiting my protein to 1.5 grams per Kg of lean body mass (I'm probably closer to 1.2 grams/kg per day) and the weight loss continues at about .35 kg per week. I suspect my ideal weight will wind up somewhere around 75 kg. I want to look like one of the Masai Warriors in the picture I am attaching, only an "older model". Paul out :-)