http://glucerna.com/product/mealbars.aspx
There are alternatives. GOOD alternatives.
I'm not a regular flyer, in fact I took three round trips within the country last year and that was a RECORD!
I'm diabetic, I carry snacks. I make sure I'm prepared to be stranded at an airport with my test supplies, medicine, and food.
I try to plan NOT to get hassled by TSA because it's not worth it to me to win their game. Maybe someday we will be able to carry a stupid bottle of water again, but until then, I'll fight the fight outside of the terminal.