Good posts and it illustrates what I'm talking about with low carb/keto vs CICO. Really a lot of diets. Eating less is the best way to lose weight and a lot of these diets- Keto, One Meal A Day (OMAD), intermittent fasting (IF), even vegan and pescatarian diets end up being fancy ways to avoid eating as much.
Your comments about not having the willpower to do balanced eating but also keto being a subset of CICO for you because you don't eat as much are dead on. You used the Keto foods to control calories more than you used ketosis specifically to burn fat faster.
I see
@Terminalxylemsuggesting Mediterranean or pescatarian diets and
@Ministry of Painsuggesting cutting out almost all sugar and
@culdeussuggesting that you just cut calories and also exercise for the love of exercise but don't give yourself any extra calories and I totally get why all of those things are good... but they're not something that a fat guy can just suddenly wake up and do. At least, not most of us.
And on the other side of that coin, I hear other people say they lost weight doing low carb or some medically supervised diet or fasting/eating one meal a day, and then they talk about how they either put the weight back on or had to keep doing the diet that got them there because they just don't have the willpower.
It's not willpower. It's learning how to do it.
Your point about your high protein foods keeping you fuller longer is exactly right. Good news - high fiber foods do that too, and a lot of them are really delicious. Raspberries and blackberries have a ton of fiber, help fill you up and they taste so good especially when you're not eating tons of sugar. Strawberries, blueberries, kiwi, pineapple, grapes, grapefruit are all loaded with good stuff, too.
Try adding some of those back to your diet. You can have a ton of fruit for a couple hundred calories, and it will help fill you up. Put the berries on some greek yogurt or make a smoothie or just eat fruit salad or grill the pineapple, maybe wrap some prosciutto around it. Or eat a piece of grapefruit for breakfast. If you aren't excited to eat grapefruit then don't buy grapefruit. Or try one and see if your tastes have changed. Fruits taste good so it's a pretty easy habit to add back.
Then add in potatoes and bananas. They both have a little fiber but also give you a ton of potassium that you're almost certainly not getting right now. Potatoes get a bad rap these days especially from keto nerds but they're awesome in moderation especially when you aren't deep frying them. Try cooking/steaming a potato in the microwave, letting it cook for a few minutes or hours even, then cutting it into fries and grilling the fries so they get a little char. So good. No oil needed. Do the same thing with a sweet potato. Or buy a container of them from the Little Potato Company or similar and make a ton of them. If you want to get fancy, cut up some onions and peppers and cook them together. Instead of having two burgers with no bun have one burger with grilled "fries" as you add back carbs.
Personally I would recommend counting calories while you do this. But you don't have to track every calorie every day like I do because you aren't trying to lose weight right now. Just get used to what your maintenance calories look like, and how many calories are in things you usually eat so you can start to get a sense of how good or bad something is when you're about to eat it.
Like if you go to chick fil a and you want to order a number one... it says the sandwich is 440 calories and the box of fries is 400 more. Is 400 a lot? Is 840 total a lot? If someone your age/height/weight/activity level can normally eat 2000 calories a day then you could have a decent breakfast and eat a sandwich and fries for lunch and again for dinner and not go over for the day.
What about that entree at my favorite restaurant? 1500 calories? Oh crap, that's almost my whole day. Maybe I should plan ahead and "save room for dinner". Or go for a long run. Or only eat half and take the other half home. Some of those places you can easily get 3000 or more calories with their sides and they're trying to upsell you appetizers and alcohol. And that's probably fine once in a rare while. Just get used to the numbers and understanding how that stuff all works.
Losing weight was a goal. You used keto for that goal and did awesome. Maintaining your weight is a goal. You've been using keto for that goal too and it's not as awesome. Getting good nutrition is a goal. Especially at our age. And keto blows for that, even if you're taking multivitamins. Enjoying all kinds of food is a goal. It's cool to be able to eat with your non keto friends or cook something that everyone likes or order that favorite comfort food at a restaurant. Invest some time in learning how that stuff works.