Why is it things that are bad for us now wheren't back in grannies days?

both grandparents are late 90's til this day dont watch a diet n are not fat can move fairly well have no real issues besides lil memory lost still eat bacon,eggs,burgers etc. 1 of my grandma drink liter pepsi daily grandpa drink pint rum a day n they well so why now all this obssession with fats and sugar........to add more my gf works in a old folks home them people junk food heads, smoke like chimmineys, yet they walk, drive shoot pool just wish they was a specialist with a good answer why the hell the better to be nicole richie skinny becuase its bad and nasty to be fat metality..