“The Diet,” is the third episode in season one. In this episode the foursome (Lucy, Ricky, Ethel and Fred) have just finished eating dinner, and everyone, except Lucy, is admitting that they have gained a few pounds. Lucy swears that she still weighs the same “110” that she did when she got married. After Ricky brings out the bathroom scale, she sees the proof that she has gained 22 pounds and now weighs in at 132. Right on cue, after this discovery the phone rings and we learn that Ricky’s dance partner cannot person and he is in need of a new girl. Lucy wants to be in show business and begs for a chance, but Ricky tells her she’s too fat. This spurs on the theme of the show; Lucy must loose this 22 pounds as soon as possible!
When Lucy shows up to the audition, one of the girls tells her that she has known Ricky for a long time and that Lucy, “is not his type.” Ricky comes in and asked the girls to audition and everyone is doing a splendid job except poor Lucy who has two left feet. The costume is then presented, a size 12, which all the girls must be able to fit. Lucy is the first to try and rips the poor costume, which shows she needs to loose that 22 pounds for sure.
When we get back from commercial we see Lucy exercising and Ethel weighing her in to see her progress, 2 pounds in 2 days. At dinner poor Lucy is eating barely anything while everyone else is enjoying a lovely steak dinner. She is so starving she hides under the table with the Mertzes’s dog (which only appears in this episode, ever!) to get scraps.
Desperate, Lucy rents a sauna to try and loose the last 5 pounds she has left. She loses the weight and goes off to the club to perform with Ricky. Ricky seems shocked when she walks out in the costume to perform with him. Surprisingly Lucy performs well (with her own silly spin on the dance, including funny faces and gum chewing) and they are a hit. Lucy cannot perform with Ricky again, because now she has to go to the hospital for malnutrition! That silly Lucy!
Some funny trivia about this episode is that Lucy does her “eeugh” sound to show she is in trouble. This is also the first episode that we learn Lucy’s maiden name, McGillicuddy. Her maiden name was originally going to be “Teitelbaum,” but was deemed “too Jewish. Another funny fact I found was that this episode, same as episode one, was based on one of the episodes of, My Favorite Husband, but it fit at the time because of how Lucy had just recently given birth to Lucie and hadn’t lost all of her pregnancy weight yet.
This episode was rerun in season 2. The new “flashback” opening has Ricky talking about how Lucy has been working out a lot at the gym, trying to get her pre-pregnancy figure back. This leads in to the memory of the last time Lucy went on a diet.”- I Love Lucy Wiki
Information gathered from watching the episode and from I Love Lucy Wiki