This is the 4907th most frequent Japanese word.
痩せ
"痩せ" (yase) means "thinness" or "slimness."
Here, 痩せました (yasemashita) is used as a past tense verb meaning 'lost weight', showing personal physical change.
彼は運動で痩せました。
He lost weight through exercise.
In this sentence, 痩せて (yasete) is an adjective form used to describe an appearance of thinness.
この服は痩せて見える効果があります。
This clothing has the effect of making you look thinner.
The term 痩せていけば (yasete ikeba) is a conditional expression indicating the process of becoming thinner could lead to positive outcomes.