slenderize
verb [ I or T ] US uk/ˈslen.dər.aɪz/ us/ˈslen.dɚ.aɪz/
（使）苗条;（使）变修长
to become thinner or to make something appear thinner
We manufacture undergarments that tone and slenderize. 我们生产健体塑身内衣。
Wearing dark clothes from the waist down will help to slenderize your figure. 下半身穿深色服装可以使你显得瘦一些。