The thing about Keto is, it isn't a diet.
It's about eating to change the way your body fuels its energy. Instead of burning sugar for energy you burn fats. Fats you eat and excess fats your body has stored.
Yes you cut out complex carbs - rice, bread, potatos and pasta because they immediately turn to sugar as they're digested. People that are diabetic will probably know these cause insulin spikes and in fact carbs never satisfy hunger they just make you more hungry and therefore likely to eat more.
You can eat meat in moderation. Fish is generally great, salmon, shrimps, sardines etc especially those high in omega 3 and other fatty fish high in nutrients and vitamins. Cheese is ok too.
Obviously processed foods are out. No ready meals, cakes and biscuits other than those made probably yourself to a Keto recipe and there's lots of options on the numerous Keto recipe web sites.
Good fats are in, avocados, nuts, cold pressed olive oil, coconut oil, butter... in fact a high intake of good fats is essential as that's what you're training your body to burn for energy instead of sugar.
Vegetables overall are good, and fruits because of the higher levels of 'natural sugar' to a lesser extent. Eating vegetables and fruits with a low carb content and or have a high fiber content. Fiber content can be deducted from the carb content to give you the exact actual carb impact.
Also the glycemic load of foods, those that slowly release sugar as opposed to those that give you an instant hit and insulin spikes, the latter should be avoided. For example lentils are a complex carb but they have a slow glycemic load and lots of fiber so I haven't personally excluded these.
I got interested in modifying my own eating after a friend was diagnosed as at risk from Diabetes. As a scientist and teacher he did a lot of research which I personally feel I've benefited from. No one talked then about Keto it was just something I discovered as I did my own research. I have to say I balked at the idea of increasing my intake of fat and certainly haven't increased it as high as suggested.
If you have a sweet tooth like me then chocolate made with 70+ cocoa is a superfood and I find a couple of pieces instead of a whole bar is enough. Nuts if you're peckish are full of good oils, potassium and other essential nutrients.
I've really enjoyed experimenting with new meals and snacks and now they're an integral part of what we eat. After a while you don't miss bread, rice or pasta at all and the benefits of a flat instead of a bloated stomach are worth any initial inconvenience.
These are just some of the things about Keto I've picked up along the way and I'm by no means an expert, nor follow a programme, or even count carbs. I'm just aware the more I learn, about what I can eat or get away with eating.
It does take a few weeks normally before you'll see any significant results but after a couple of months you'll definitely see the kilos disappear.
By the way my friend has reversed his at risk from Diabetes diagnosis.