Greetings and thanks for this very important thread helpful to Weight Watchers the world over
Being a new San Diego resident I can say while In and Out and certainly puts out a good milkshake you might want to also check out "Hodads"
A very impressive milkshake.It was voted as the "Best of San Diego" in the most recent San Diego Magazine.I don't usully agree with their best of awards which are usually a narrow group of opinions.However as any taster knows all taste opinions are highly subjective.
Hodads certainly gets high marks IMO.
We went for their well known burgers but were far more impressed with the milkshakes.And the cool surfer/beach crowd.The lines to get in would probably keep me away however