My grandma developed type 2 diabetes in her late eighties. She’d been 2-3 stone overweight since her forties.
It absolutely terrified her and she she was pretty ruthless in her diet after that.
Her approach was based on what my grandad used to do when he wanted to drop some weight when he was a boxer when he was young (and they were courting). He just used to say “cut what you eat by half”.
So between portion control and swaps she halved her caloric intake. Permanently.
So no more frying or sautéing. No oven chips or breaded foods.
Breakfast became high fibre cereal and skimmed milk, with half a grapefruit. She would have bacon and eggs at the weekend, but one egg, one rasher of bacon and cooked in the microwave so no extra oil.
Lunch went from being soup and a sandwich to being soup and one piece of toast made from light bread (and it was now always homemade broth- chicken stock, carrots, onions celery and a very small amount of pulses and barley, no cream of mushroom or anything hearty).
Dinner was always a small portion of meat or fish, a small potato (boiled) and made into potato salad using yoghurt not mayonnaise and two portions of vegetables.
She stopped keeping sweets or nice biscuits in the house (she quite one packet of plain biscuits she didn’t really like in a slightly open Tupperware so they went soft and weren’t tempting, but she had something quick if she was desperate).
Whilst she was losing weight she ate no snacks whatsoever. She lost 4 stone in a few months. Once she’s lost the weight, and reversed the diabetes, she kept light crisps and light choc ices in the house, and allowed herself to eat a small cake or baked good (e.g. scotch pancake once a week).
She limited herself to one coffee a day and three cups of tea with a splash of skimmed milk.
Once a week she’d go to my aunty’s for a meal and eat much more calorific foods and pudding, but she started asking for a half portion.
It took an iron will, but she lost the weight and kept it off. She lost another 3/4 of a stone in her mid nineties when she stopped going out on her own and her appetite just fell away.
She lived to just shy of 101, living independently in her own home with no more assistance than getting her shopping delivered and insisting medical professionals (doctor, chiropodist) came to see her on the infrequent occasion she needed to see them.