Bullet-prof diet

So for the past 2 weeks, I have been on a 'Bullet-proof diet' developed by a bio-hacker of a Silicon Valley.
He has tested everything on his own body, using latest technology and rationalizing based on science.

In short, his conclusion is,
- drink 2 cups of coffee with 2 tablespoons of grass-fed butter and 2 table spoons of coconut oil
- for lunch and dinner, as much vegetables as possibles + grass-fed meat.
- no dairy products, not many fruits, little carbs for dinner.

I have been following quite well, but then I gained weight.
Close to the end of a book, there is a phrase,
after low-fat, low-carbs diet, it may time for your body to get used to digesting fat (oil/butter), so start with little amounts of fat.

This writer tends to explain everything too long.
I have been putting too much fat, apparently.

And this diet is NOT for college kids.
What do you do, when your friends ask you to eat out?
Should I be like,
sorry, I am on a bullet-proof diet, so I cannot eat any carbs?

Last night, we had a chill gathering at someone's apartment and I had quite some chips.
After that at 3am we went to get McDonalds.
Yes, I did go.
Because, chatting with friends is a great part of our lives.
people with strong friendships live longer btw.

anyway, today my brain worked worse, just like the author warns.
Anyway, I will have to lose this extra kilos I gained thanks to bullet-proof diet.
HOW though...