Metabolic Flexibility – The Ability Toe Eat Carbs and Protein Without Gaining Weight – Once Lost Can We Ever Get It Back? As always the answer to almost any question is – “it depends”.
First the less insulin resistant that a person is the more “metabolically flexible” they are. This is the doctor way of saying, if you haven’t damaged your liver and pancreas with years of consuming large amounts of either refined sugar or alcohol which are the 2 major substances that lead to fatty liver and pancreas and the accompanying insulin resistance you should be able to tolerate large amounts of both carbohydrate and protein in your diet and not get fat. About a 1/3 of the population seem to be able to consume all the refined sugar and alcohol they want without developing liver or pancreas damage. With regard to the question, “can you ever heal insulin resistance which if you have developed it, is usually but not always accompanied by getting fat (see my post: “Are You a “Skinny Diabetic”? 1 of 10 Diabetics Is Not Obese! They Are Called TOFI or MONW.”)? The answer is – sometimes you can heal the damage and regain your “metabolic flexibility”.
To my knowledge this has not been studied in clinical trials but I have been following low carb experts, blogs and Facebook groups for over 5 years and it appears to me that the younger you are when you go low carb, high fat to treat insulin resistance and the shorter the time you were impaired the more likely you are to regain your metabolic flexibility. The only way I know for anyone to find out is just to try to add back the carbs or protein that they want to and follow their abdominal girth and hemoglobin A1c (a measure of a person’s average blood sugar for the last 90-120 days) and if either starts going up then they are probably not one of the lucky “reversers”.
Where I see this most often is in people who do Zero Carb (only meat, eggs, cheese and butter diet) using the “all the meat you want” approach without limiting protein or increasing fat. The people who are more “metabolically flexible” usually are younger and have been fat for only a few years. These younger folks tend to do amazing eating all the protein (meat) they want while people like me who abused refined sugar for 62 years often don’t lose weight or even gain on the unlimited protein approach. And if after losing weight using the limit protein, add fat and intermittent fasting approach that I recommend, when us severely damaged folks try to add more protein or carbs back into our diets we quickly regain weight and see our laboratory values for blood sugar, blood fats and inflammation go in the wrong direction, while the younger, “fat for less time” crowd often can regain metabolic flexibility on the “eat all the meat you want” Zero Carb style and other diets which contain more carbs and protein without regaining weight worsening inflammation or blood sugar control. PS if you you want to know how insulin resistant you are here’s a link. A caveat is that if you have been on a low carb, high fat diet for a while the numbers may look really good only to quickly go sour should you increase carbs or protein if you haven’t regained your metabolic flexibility.
As for risk of heart attack if you add back carbs and protein after losing weight on a low carb, high fat diet like Zero Carb, here’s my opinion: Heart attacks are caused by inflammation. You can read about the process in detail in my post: What Causes a Heart Attack? Ketogenic diets like Zero Carb and other Low Carb, High Fat diets make the markers of heart attack risk all go in the right direction. I wrote about that in this post: I Went Zero Carb and My Total and LDL Cholesterol Went Really High! Is That Dangerous? No! If you add carbs or protein protein back into your diet you should follow a blood test called “C-Reactive Protein” (CRP). It is the marker of chronic inflammation used by doctors and researchers most often and is a highly predictive of heart attack risk. If you haven’t regained metabolic flexibility then it will definitely rise. Mine has remained less than 1 (very low) since going low carb, high fat and that is what what they’ve seen in most large studies of low carb high fat diets. Here are the one year results from the Virta controlled trial comparing 250 diabetics on low carb diets to patients on the American Diabetes Association recommended diet and medical care: