I just found these the other day (sorry if they've been mentioned before). They aren't marketed as "diet" ice cream, but they have 160 calories, so pretty much the same as a skinny cow.
Birthday Party Ice Cream Sandwiches
A party in a sandwich! Creamy white birthday cake flavored ice cream with colorful confetti sprinkles and swirls of blue frosting between two vanilla wafers.
Under 300 - 299 lbs - MET 4/20/13 * Lowest in 5 years - 274lbs - MET 6/10/13 * Halfway to Goal - 257 lbs - MET 7/25/13 *
100lbs down - 250 lbs - MET 8/7/13 * Lowest in 10 years - 236 lbs - MET 9/19/13 * 75% to Goal - 211 lbs - MET 12/5/13 *
Onederland! - 199 lbs - MET 12/31/13 * Overweight BMI - 196 lbs - MET 1/11/14 * High School Low - 174 lbs * Healthy BMI Goal - 164 lbs
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