Dieter No-No is a term used to describe foods that are unhealthy and should be avoided when trying to lose weight. The crossword solutions for Dieter No-No include Fattener (8 letters), Gaining (7 letters), CHEESECAKE (10 letters), FAT (3 letters), SNACK (5 letters), Sweets (6 letters), and CARBS (5 letters). All of these foods are high in calories and can lead to weight gain, while the solution LEAN (4 letters) is a healthier alternative.