An empty tin weighs 30g, all metal, mostly steel plus a few other metals for coating.
The cat lives about 15 years, but for the first year or two he eats less, say half. Then we have 2 years half and 13 years full. 2 years half means one year full: inverse proportional because with the same food he will eat fewer years if he eats more at each meal.
a tin
the cat
(regrettably died end 2004)
In his life, that's 13+1=14 years full diet. He eats every day, 365 days a year, two tins a day: 14x365x2 = 10'220 cans.
(1 day corresponds to 2 cans, then 365 days corresponds to 730 cans; 1 year corresponds to 730 cans then 14 years corresponds to 10'220 cans).
A total metal consumption of 30gx10'220 = 306'600g which is 306.6kg.
A single pet cat consumes 307kg of metal!