[dublinben]

According to the CDC, over 70% of American adults are overweight or obese, so by targeting a "large cross-section" of the population restaurants are in fact aiming at 'large' customers. This reality isn't represented in advertising for obvious reasons.

https://www.cdc.gov/nchs/fastats/obesity-overweight.htm

[kube-system]

Specifically targeting a population, and the coincidental demographics of that population are two entirely different things.

That 70% is part of the 100% which they are actually targeting, but only coincidentally. There are plenty of fast food ads targeting health-conscious consumers.

You could also point out that 70% of Americans are also Christian, but that doesn't mean every company that sells to Americans specifically targets Christian customers...

...also, most large fast food companies also have a significant presence in multiple countries.