I personally do not believe lifetime keto is “necessary.” Beneficial - probably. I found that when trying to gain muscle while on keto, it seemed beneficial to have a bit more carbs than I did when I started keto - the ketone count on my strips were “trace” by that time - but I still seemed to be losing inches, while gaining some weight. That seemed like a good result to me. I don’t know if you want to call it keto though… As I have said, I continued to lose weight even after quitting keto - I believe by continuing to eat some MCTs. I think that kept my fat burning on… I was eating some sugary desserts by that time, and eating a non-keto peanut butter, banana and raisin sandwich by that time almost every morning. So my breakfast was around 1000 calories. I believe keto was valuable for ramping up my metabolism a little bit - I actually was eating quite a bit - you have to to get 100-150 gr of protein in every day. It turned on my winter “fat-burning mode” as I call it, and that allowed me to probably gain some brown fat. I kept that process on by eating MCTs even after quitting keto.
Do I think keto would be good the rest of my life? Maybe. I see no problem with it done the way I did. That is why I chose it. My movements were quite regular and quick. As I have said I have had a few episodes in my life where antibiotics damaged my gut biome. The first was in my 20s, and the recovery was a long, hard learning process. It took me over a year to fully recover from that. That made my experience in 2020 more informed, and manageable, but it was still bad for a good month or two. I had lots of gas and discomfort. So I know at least some of the problems people can have eating plants when their gut biomes are damaged. That is why I strive to repair mine. That is also why I am very leary of going full carni. Once I am doing well, I do not want to risk damaging my gut biome. I know from past experience how bad that can be for me.
To answer your question more directly, I believe we are designed to eat meats and carbs. We are designed to eat nutrient dense foods. We are not plant eaters like cows or other ruminants. We need more concentrated nutrient plant foods. But in the fall, those fruits and carbs can put some fat on. We seem to be designed that way. It helped hunter gatherers survive the winter. But in the winter that shifted to a more ketogenic diet, and the ketones turned on the fat burning process - our mitochondria in our fat cells got their fat burning turned on with ketones, and uncoupled. That doesn’t happen in our muscles. The ketones don’t cause the mitochondria in our muscle cells to uncouple. Why is that? Because it is not advantageous to burn up extra fat when you aren’t using your muscles in the winter time. You would want your muscles to be efficient as possible so as not to use up all your fat stores.
So, that cycle is not a lifetime keto diet. I’m not saying it has to be, to be healthy, but I believe there are a lot of health advantages to learning what plant foods you do well on, and eating them. I quite enjoy the variety that way. I don’t think there is a large proportion of centenarians who are vegan. That presents health challenges for us - especially in building muscle. But, I also don’t see a large nuimber of centenarians who are carnivores. Maybe some people do better that way, but my approach would be to first try to heal my gut before trying carni. My personal belief is that if I have a diverse, healthy gut biome, I will be able to eat most plant foods. We are seeing a lot of people developing allergies. I understand that. I’ve had two anaphylactic episodes myself. For instance, it seems that people who don’t have a certain variety of Clostridium are likely to develop a peanut allergy. I believe there are just many things which can damage our gut biomes these days, and it is hard to know what to eliminate in order to address digestive problems. So, I take a shotgun approach to gut health, and throw a ton of things at it if I have issues. This last antiobiotic episode caused me to learn about bacteriophages, and use them… That was something completely new to me. But, I do believe it did something, because I became quite gassy for a few days - probably when the bacteriophages were attacking bad guys through their biofilms. Changing diet alone is not going to get rid of all those bad guys, but I did that too. I took the widest variety of probiotics I could find. I just threw the book at it, and got better much faster than 30 years ago. These digestive issues I’ve had just cause me to be very cautious, and not to want to do anything which can damage my gut biome. The style of Keto I adopted allowed me to do that as I have said. I could eat my veggies(fiber) and concentrated protein sources. I have said elsewhere that I consider myself to be a “hard gainer,” but that is in regards to muscle. I think I gained more muscle in that 4 month period of keto than I ever have in my life in that amount of time. I was just really impressed with my results. I enjoy eating some “saturated fats,” but I am typically not one to eat them just to eat fat. My new exception is MCT saturated fats. I now plan to include them year around to keep me a little more fat adapted. I eat other saturated fats for taste and satiety, but not for health reasons. I don’t particularly see them as being healthy… they are just a source of energy… they aren’t the boogey man they got painted as by Ancel Keys, and they generally are not going to make you fat unless your insulin is high. So, I don’t view myself as eating a high fat style of keto. I mostly just eat whatever fat is coming with my protein sources, and that keeps me satiated and happy. That ends up being keto if you cut the carbs enough. I do believe there are healthy fats, and they are in this order: 1. MCT fats, 2. unprocessed omega 3 and omega 6 polyunsaturated fats from their natural sources, 3. saturated fats, and monounsaturated fats.
All other fats are unhealthy imho 1. trans-fats, 2. refined polyunsaturated fats.
I believe this is why we find vegans and vegetarians with cardiovascular disease. Many have become so because they believed saturated animal fats are harmful, and wanted to avoid them, but we see they get cardiovascular disease anyway… probably because they switched to seed oils…maybe in combination with sugar. In nature these three fats always occur together: saturated fats, polyunsaturated fats, and monounsaturated fats. I believe they are all OK, and some are necessary. It’s the man-made fats that are the problem. Otherwise, we need to dispel the fat phobia still in much of society.
Just a lot of very sweet fruits (I actually only want a taste but if I eat my super soft, super easy to eat pears 10 times a day…) but let’s not talk about that now.