Wobblybits my OH is also tall, heavily built and spent years travelling the world for work. He has arthritis and though he does a lot of work in the garden, he can't walk very far because of joint pain. For years he was borderline obese and developed high BP, high cholesterol and pre-diabetes.
We have been low-carbing for two and a half tears and it has been brilliant. He has lost three stones and kept it off, come out of pre-diabetes and his BP and cholesterol are down.
He can still enjoy beef marbled with fat, dry wine, cheese and eggs and bacon. Our daily diet is high in veg, olive oil, fish, lean meat, salads, avocados etc.
We don't have cakes, puddings or excessive amounts of fruit. We don't have rice, bread, potatoes or pasta except on very rare occasions.
We don't count calories or exercise to lose weight.
We have no trouble sticking to the diet.
It works.