Where is your first sentence coming from though? Afaik keto works well by stabilizing and lowering insulin release with the effect of minimizing the storage of fat and carb cravings caused by sugar crashes. If you want to you can literally skip a meal without becoming grumpy, lightheaded or ravenous. Also: how can a diet composed of meat, fish, cruciferous and green leafy vegetables, cheese, nuts, berries, fatty fruits like avocado and olives, and healthy oils be one of the least nutritious diets around? A vegan diet is clearly scoring much worse on this topic I'm afraid. To give you an example in this study where different foods are evaluated based on their micronutrient density (in an attempt to combat malnutrition) you'll see that the top foods are all of animal origin: https://www.frontiersin.org/articles/10.3389/fnut.2022.80656...

Results: We find that the top sources of priority micronutrients are organs, small fish, dark green leafy vegetables, bivalves, crustaceans, goat, beef, eggs, milk, canned fish with bones, mutton, and lamb. Cheese, goat milk, and pork are also good sources, and to a lesser extent, yogurt, fresh fish, pulses, teff, and canned fish without bones.