Being a native of Ukraine, it’s hard to choose the most unhealthy food of Ukrainian cuisine, as healthiness seems to have been among the things which bothered my ancestors the least when developing their recipes. From my experience, I would name these Ukrainian foods as the most unhealthy:

Škvarky (шкварки) – basically fat taken from internal organs of domestic animals or birds and fried on a pan. I feel my cholesterol level rising after just looking at the photo.

Krovjanka (кров’янка) – pig intestine filled with the pig’s blood, fat and meat, as well as gruel, milk and other ingredients. Frequently fried on a pan to increase its fattiness.

Perepička (перепічка) – meat sausage covered in dough and deep-fried in oil. Popular as street food in big cities due to its high energy content.

Bil’aš (біляш) – similar to the previous dish, but filled with ground meat of dubious origin.
The diet in Scotland is not know for its nutritious value. We fry everything

Lets start with a deep fried mars bar. I have to be honest I’ve never had one but the look pretty grim.
A typical Sunday morning breakfast would be…

But the real reason Scottish people live shorter lives than the rest of the UK has to be

Hmm what is that? Its a cheap pizza deep fried. The fat soaks into the bread while it fries and I have to say ever bite leaves a wet mess of grease on your lips. They taste great but not good for you.
Oh wait. Someone has made it worse!

Yes thats a pizza dipped in batter before frying! I have no idea how many calories are in one of these but if I had to guess they are not good for you.
Netherlands: the “Kapsalon” (litterally “the hairdresser’s”). Legend has it that this was a special order by a specific hairdresser, and the name stuck.
It’s french fries, covered with kebab or shoarma, cheese and sauce.

Czech Republic here.
The entire Czech cuisine is not particulary healthy, definitely if we compare it to the Mediterrenean. As a landlocked country located north of Alps, its cuisine consists largely of carbs and red meat (mostly pork), often deep-fried.
To demonstrate, lo and behold the Czech national dish, the svíčková:

“Sirloin steak prepared with vegetables (carrots, parsley root, celeriac and onion), spiced with black pepper, allspice, bay leaf and thyme, and boiled with double cream. It is generally served with bread dumplings”.
But if I am to point my finger at what I think is the unhealthiest one, my choice would be this:

“A slice of cheese (which is usually Edam, but may also be Hermelín or Niva) about 1.5 cm thick is first breaded with flour, egg, and bread crumbs and then fried either in a pan or deep-fat fryer. It is typically served with tartar sauce or mayonnaise, and fried potatoes”
– French fries, crocquettes or larger chunks of deep-fried and seasoned potatoes which are called “americké brambory” (American potatoes).
Fried cheese is not unlike Fish and chips, and belongs among typical pub foods, hence it often teams up with beer (like most Czech dishes, anyway).