slim
v.v. to lose weight or become thinner, often by eating less or exercising more. You use this when you want to look more fit or healthy.
v. to reduce one's body weight or physical girth, typically through dietary restriction or physical activity. Often used with the particle 'down' to indicate a completed process.
She wants to slim down before her wedding next month.
He managed to slim down significantly by cutting out sugary snacks and walking to work every day.
The athlete needed to slim down to meet the weight requirements for his specific competitive category without sacrificing his overall muscle density.
Often functions as a phrasal verb ('slim down'). It is intransitive when describing the person's change, but can be transitive when describing the effect of a garment or diet.