Paul Saladino· MD
of the main roles of insulin in my mind is anti catabolism which means that it stops you breaking down tissue everybody thinks that the role of insulin is to shove glucose into cells and I think that that is the case because that we discovered insulin and we focused on insulin because of type 1 diabetes and the treatment of type 1 diabetes in type 1 diabetes you have to take exogenous insulin you have to inject it because you don't you're not making any and in that scenario you're injecting insulin peripherally at a dose that will push glucose into cells one of the one of the ways that it controls blood sugar though is by acting on the tissues muscle tissue fat tissue to not break down and deliver gluconeogenic substrate to the liver so the liver is making a lot of this glucose and then you are stopping the supply of substrate because it we owe unabated no insulin your muscle starts to break down your fat starts to break down the amino acids fatty acids glycerol I just delivered to the liver and the livers like crap I better make glucose out of this because that's all I can do and again there's no insulin so there's no breaks on the liver doing that so the liver just pumps out all this extra glucose and all of this is kind of conflated because if you inject insulin the glucose goes down you're assuming oh yeah that's because the glucose been shoved into a cell it's not just that it's also that the liver is making less glucose and in type 2 diabetes that is where most of the glucose is coming from is unabated gluconeogenesis in the liver and that is happening because the fat tissue particularly but also potentially the muscle tissue is insulin resistant it is said no more insulin for me I have enough energy on board in my cell not using so you can't shove any more into me and then you get to a point where they start to break break down you have amino acid turnover in the muscle you have fatty acid turnover in in the adipose tissue and those are then delivered to the liver which again has this it's partly supply driven like this stuff just shows up and it's like well what am I going to do with it its glucose is less toxic than having loads you know loads of glycerol and free fatty acids and all this stuff just like floating around so I'm going to turn into glucose and and this is why the states are so different in physiological insulin resistance work blood glucose is low because you're not getting in any in through the diet and then you have tissues particularly the muscle tissue which can adapt to using free fatty acids released either from the diet or released from the adda pretties from the adipose tissue if you if you're in a deficit and then there are some tissues in the body that do have a requirement for glucose they can't fat at that particularly certain the cells in the brain and the red blood cells so you need whatever glucose you have to be spared for those for those cells so the muscle tissue says do you know what I can run on fat so I'm just going to turn off this insulin signal and you don't need to give me any glucose because I'm sparing the glucose for the rest of the body and in that state yes you will also have elevated free fatty acids like you do in type 2 diabetes we are very low glucose so there's a completely different States this is the body and because of the role of insulin this is the body deciding where which nutrient should go because nutrient partitioning is insulins essentially its main job and that is insulin acting correctly in that state you don't have enough glucose to run all the cells in your body so the body selectively says this can run on fat this needs glucose so it's gonna be spared for those tissues but what happens is then if you give somebody a boatload of carbohydrate and they've been on on a keto diet for a long period of time those cells have still turned down the insulin signal right so you're gonna get this massive spike in blood sugar and say holy crap this guy's has insulin resistance but if you had to meet some carbohydrates for three or four days you know this is probably somebody who in that interim improve their lean particularly if they were overweight or instant resistant before you know they've improved their body composition potentially maybe lost some weight you know their metabolic health has almost certainly improved but you just need to give them some carbohydrate for them to like turn that turn that signal back on so this is its complex physiology really no whiteboard I love this conversation so what Tommy is saying I'll just try and summarize it or re regurgitate it for people in a different way and hopefully it'll become even more clear during states of low carbohydrate consumption of a diet the body does something that is natural called physiologic insulin resistance at the level of the muscle or glucose sparing is probably a better word and so what's happening there and there are studies which show that even one low-carb meal at night can do this and so pregnant women who are doing a glucose tolerance test or a glue cola the next day should not be doing a low carb meal or they can do a low carb meal if they want to but if you do if a pregnant woman does a low carb meal the night before a glucose tolerance test they can look insulin resistant the next day because that test is sort of flawed right and what's going on there is that when we increase the amount of fat in our diet and when we decrease the amount of carbohydrates there are different signals from the adipose tissue because of declining levels of insulin right? what we know is that if we don't eat carbohydrates if we eat a high if we eat a high fat low carb diet with a moderate amount of protein insulin signal drops