Hello. Welcome to the forum. I'm not sure why you think you can get good answers in a VEGAN forum. But I'm glad you thought you would try.
First off I probably need to disclose that I am severely biased against Keto diets. I probably should recuse myself but I think my biases were created by facts not fiction.
Keto is one of the worst diets that are being sold to the public.
There are new studies showing Keto is linked with cancer, kidney failure, and heart disease.
And it IS unsustainable. All of the doctors who have written Keto Diet books say (usually in the first chapter) that it is a short term diet and not heathy to stay on for longer than 6 months. Most of the doctor recommended plans are for 3 to 6 weeks.
The one good thing I can say about Keto is that it IS effective. People on the keto diet DO lose weight. However studies show that people who lose weight rapidly (including keto dieters) are likely to gain it right back.
Weight loss isn't even in your list of objective so I don't know why you would even consider Keto a good idea.
I'm not sure what is in your Keto breakfast but it must not include many carbs. Perhaps your previous non-keto breakfasts had something in them to created brain fog. and all you have to do is eliminate that.
The thing is low carb diets are just bad. It turns out that carbs are really good for you. Fruits and vegetables are high in carbs and they are also high in all your vitamins and minerals.
A lot of nutritionists talking bout diets categorized by the percentage of Carbs, protein and fats.
Keto is generally a 10-20-70 diet. The concept is that by eating very little carbs you force your body into ketogenesis. I really don't understand why anyone would do that. I know that there are some benefits but it just doesn't seem like a good idea to me.
IMHO, a better diet is one that is more balanced. Something like a 60-20-20 diet.
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I just scrolled thru this thread. I suggest you go back to the beginning and read some of the posts.