The practical side of the LCHF diet

The theory is simple enough: no "man-made, unnatural" products are allowed. This means no trans fats (margarine is one of them) as they are really bad for your health. This has implications: no fast food (fries are fried in these trans fats), no foodstuff where these fats are used, this means you have to read the labels and find out if there are any trans fats used to make the product. Most products that you know if made at home should be in the fridge but are outside in the shop have either loads of salt, sugar or trans fats.
Which fats are allowed then? Natural saturated fat, like the ones present in butter and cream, animal fat (found in meat), and all the "good fats", olive oil, avocado, etc.
Also this ban involves "fake sugar", so all the artificial sweeteners are also prohibited. No diet coke, sorry.
So, what is the "carb" that you set to "low": sugary and starchy foods. Sugar is completely banned and the starchy foods, depending on the amounts of carbohydrates and the level to which the person desires, are also banned.
So, how do you "put into practice" the LCHF diet? I will talk about this diet to go down on weight only, not as a permanent lifestyle choice.
There are several steps to follow.

1. Clean your fridge and pantry: remove all sweet things like cookies, spreads, jams, marmalade and fruits (yes, fruits). Remove also all starchy things like rice, pasta, cous-cous, quinoa, bulgur, breakfast cereals, polenta, potatoes, sweet potatoes, carrots, legumes, paprika (this will depend on how strict you want to be). If you are super strict, then things like ketchup are not allowed (contains sugar), or soy sauce (also contains sugar or starch). Check up things like sausages, mayonnaise or sugo, they should not have carbs but very often they do. Be wary of all the sauces and things you use that are already made (pesto, salad dressings, sauces, etc). There are gray zones, and depending how strict you want to be, if you allow them in your diet or not. Lentils are rich in carbs but also rich in protein. Same with quinoa. Paprika can have a lot of carbs per 100 gr (10%), but it also comes with loads of fiber, so treat with care but allow it in the diet. What I did myself (because I don't want to throw anything away) is to put all those non-perishable foods in a box, for when the diet is over.
2. Shop often, because the food will be fresher. What can you eat? Eggs, meats, fish, nuts, cheese (full fat versions of it) and vegetables. The biggest problem is to have something to eat the meats with (you cannot have salad all the time!). The Internet is full of suggestions to fake the missing pure, rice, pasta. Chef William (link on the left) is an inspiration for me. The mashed cauliflower recipe is just delicious.
3. Add fat to the food to make it filling and satisfying. This was the hardest for me. After years of listening to the "fat is bad" advice, I had become a fat-phobic. You need to add fat to the diet, otherwise you end up eating way too much proteins, and a protein-rich diet is not good for your health. So you have to get used to make sauces to go together with your meat (gravy, cream and cheese is one of my favourites). Salad made with avocados are a good idea. Add fat until you are satisfied and not hungry.
4. With care and aware of your own response to it, a very moderate amount of (dry, not sweet) wine and berries is allowed. I respond well to wine, but if I eat a handful of berries, I get crazy for more sugar. I cannot eat (at least for now) anything remotely sweet. 
5. Treat fruit like you would candy. Not very often. I cannot eat any fruits now myself (and therefore I am taking a vitamin supplement) but I am hoping my insulin levels will go to normal and later be able to enjoy an orange without going out of ketosis.
6. Most important: eat only when hungry. Tweak your fat intake to end up hungry at the right moments (here in The Netherlands people are rather strict with times for the lunch pause). And never go hungry. It is counterproductive, as then the body goes into starvation mode and then you cannot lose weight. The whole idea is that you are happy and satisfied, but forcing the body to process protein and fat mostly, and going into ketosis.

I follow this diet without looking for the carb content of every thing. I would get crazy like that. I also don't want to get quotas to fill on each type of nutrient (there are apps for knowing how many carbs, protein and fat you eat per meal). I have a busy life as it is. I have banned all starchy foods (grains, potatoes, carrots, legumes) but I eat paprika without worry. I take it easy with the fat, I just cannot drink "bullet coffee" (coffee with butter), I find it gross. And also take it easy with nuts. That's it. It is actually a quite simple diet, as you don't count portions, calories or anything else. And it works.
After 4 weeks, I have gone down 7 kilos already (a lot of water though) and my boyfriend has gone down 4 kg (no water there, guys are lucky on weight issues). I think of those kilos we lost, 2 kg each is probably the real weight loss. The rest is the water retention part caused by the sugary things we used to eat.