No idea what "fee-fi-fo-fum" is supposed to refer to, but it seems you're suggesting that Glaswegians simply choose to have a poor diet and therefore suffer poor life expectancies as a result. In reality there are myriad social and health problems that come from having a shitload of deprived areas - can be seen in the link Arethuza posted - and all of these contribute in some way to a lower life expectancy.
If you're going for cheap "Scottish people like alcohol and deep fried food" laughs then, ok fair have your fun. But know that there isn't that much difference north and south of the border on that, so if you're searching for a serious answer you would need to dig deeper.
