For me, soups, salads, stir fries, fish, meat, seafood, egg based dishes are my every day.
Thank god was starting to feel like a complete freak reading this thread.
For someone low carb coming depending on how long they will be and wether they tolerate dairy. Roast a chicken portion it up, make a type of frittata by whisking a load of eggs throw in some veg like peppers and tomatoes couple of teaspoons on pesto dolloped around the top, some cheese, then bake in oven for 30-40 mins or cook in frying pan for 10 mins then under the grill at medium heat for another 10 mins let it cool then portion that up like pizza, also Greek yogurt or Greek style yogurt full fat, some walnut halves or almonds, boiled eggs and a selection of some veggies than can be eaten raw let them know they can pick at those as they like. The above would cost you no more than 10 quid at Aldi's and they would be sorted easily for the weekend. If you are making spaghetti Bol just leave a portion of the beef ragu to the side and do a salad and veg. Honestly it's really not hard to cater for.
I'm coeliac and suffer from really bad ibs I don't eat all that many carbs and I don't eat gluten free shit as it's even worse than the normal stuff just full of sugar and worse. The above is how I eat on a daily basis it is great and relatively inexpensive. Before my diagnosis I ate the cereal, sandwich, pasta every day diet and I was fat and poorly. Obviously not completely comparable as I have an allergy but I do think a lot of people would benefit dramatically.
I agree the high amount of processed carbs and sugar that society eat and the sheer lack of activity is what's causing obesity and possibly a lot of the diseases that kill us today.