Is it possible to feed a cat a healthy meat diet?

I was given 3 kittens by a friend whose cat had a litter. Not wanting to separate them, I took all 3. They were great kittens, they played, they loved the house and they seemed healthy. 2 boys and 1 girl.

Now, fully grown, the top cat is a big healthy beast of a cat. More than one person has told me that he’s the “biggest cat I’ve ever seen”. About 17 lbs (7.7 kg) but not fat. He rules the house. He’s not mean, he just sits there and watches everyone. His name appropriately is Panther, but sometimes I just call him “Boss”.

The little one, the only girl, grew up picked on by her brothers. She’s soft, cuddly and cute as can be. Despite being basically a twin, she’s 11 lbs (around 5 kg) of fluff, but on occasion when she gets spooked, she’ll grab you and you get a sense that there’s some real muscle behind her fluff. Growing up she was the smallest and I think she got used to being the smallest. Her name is Peaches.

The middle one is the one I’m asking about. He and his brother as kittens were equals, but as they grew to full size, Panther added more weight to a more solid frame and Pepper, the middle cat, stayed skinny and he weighs about 14 lbs (6.4 kg) and is visibly skinny. All 3 are currently about 2 years and 8 months old.

I used to give them treats. Turkey was a favorite but when Pepper started to only want to eat turkey and nothing else, I stopped giving them that. All 3 cats went cold turkey as they say, because I know it’s not healthy for a cat to only eat meat.

The problem is, Pepper doesn’t seem to like cat food. He eats it sparingly and he’s growing skinnier. He’s stopped grooming himself as well as his brother and sister and his fur is growing a little bit oily and clumpy. I know that there could be several causes for this, but I’m also wondering if perhaps he just doesn’t like cat food and if I can try making him turkey or chicken based meals.

I know that some places sell “raw” cat food, but I’ve tried that in the past and my cats didn’t like it. It’s also quite expensive, no cheaper than turkey.

So, here’s my question.

Is experimenting with feeding him turkey again a bad idea? I am asking that in context of feeding it with proper supplements (there’s a specific amino acid I think that cats need to be fed that they get from cat food but not from meat), but I don’t remember what it is. Is that worth trying or would I just need to make him go cold turkey again if I did that?

And can canned and dry cat food be bad for some cats?

EDIT – Update a couple months later.

My cat who went on the self imposed “I just want to eat sliced turkey” diet has adapted to eating cat food and he’s back to being about the same weight as his slightly bigger brother. No longer skinny. He still begs sometimes when I open the fridge, but he’s eating cat food again. I have a soft heart and I want to feed him cold cuts, but I don’t. I haven’t bought turkey slices in nearly 3 months and he seems to have forgotten that they exist. Other meats don’t have the same pull on him, so he’s good now. So, long story short, the cold turkey with sliced turkey experiment worked.

The trick now for me, as they’re approaching 3 years old, is that all 3 are slowly putting on weight. I have to ease them into eating less now, but that’s another question.