Not to nitpik this, but I don't consider eating off the dollar menu at McDonalds anyway to save money. In the long haul--that's probably what will end up killing you or at least racking up some medical bills. I'd rather spend 10x the dollar menu at a local lunch spot with real food that won't send me to an early grave. All around, good advice--but don't use fast food as a way to slim down the budget.
He doesn't suggest eating off the dollar menu as the way to save money. Rather, if you do eat at McDonalds, eat off the dollar menu. Subtle, but distinct difference.
His best advice is probably to avoid eating out in general.