What follows is experience not recommendation:

I knew someone who tried the Adkins diet seriously and long term. He appeared to lose a lot of weight and keep it off and be healthy. I know no other details.

About fifteen years ago I tried a specific version of an administered keto diet. Mine was medium protein, low carb, and low fat. I went to a doctor's office once a week for a weigh-in, health check, and to purchase specialized diet supplements and low carb foods. It was not high expense. It worked to the extent of rapid loss of a lot of weight. It did not work for me in that I did not keep the weight off.

A "keto diet" is easy to say and write, but the point of the diet is to put your body into ketosis. This is a significant thing to do to your body so you must have a plan and a witness. You have to keep your total consumption of carbs not just low, but VERY LOW. Your pancreas goes inactive. You feel a difference. There are chemical tabs you purchase that detect the presence of ketones so you know you are in ketosis. Just eating a "keto diet" is not necessarily doing that for you. Any departure from the ultra-low carbathon kicks you out of ketosis in a hurry.

As to the medical benefits of it for weight loss, you can lose a lot of weight that way. But it is not a permanent state of affairs and unless you have a stable landing place as to lifestyle, there is no guarantee the weight will stay off. I think the other person I started with transitioned to Weight Watchers once they got where they wanted to go.

In ketosis, your brain is metabolizing differently than when you are ingesting more carbs. You do feel different, and it is neither bad nor good. The diet has been utilized for people with seizures. But that wasn't what I was doing it for.

One of my current friends with a lot of common sense and medical awareness thinks that going into ketosis for weight loss is generally drastic ill-advised and usually unhealthy. They developed a life-long habit of never finishing anything. They are slim and active.

When I was on the diet, I felt somewhat sharper mentally, but I also upped my caffeine consumption, via black coffee, significantly. Maybe there was a relationship there.