your таки надо, несмотря ни на что)

Нет, не надо: https://en.oxforddictionaries.com/definition/put_on_(or_lose)_weight

https://books.google.com/ngrams/graph?content=lose+weight%2C+lose+your+weight&year_start=1990&year_end=2008&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Close%20weight%3B%2Cc0%3B.t1%3B%2Close%20your%20weight%3B%2Cc0

можно и так, и так
https://www.google.com/search?q=%22you+will+lose+your+weight%22&oq=%22you+will+lose+your+weight%22+&sourceid=chrome&ie=UTF-8

https://www.google.com/search?q=%22you+will+lose+weight%22&newwindow=1&safe=active&ei=2HM9WoynGtDDwQLcxIHYAg&start=10&sa=N&biw=1024&bih=600
не принципиально

Словари дают без притяж.местоимения и посмотрите на частотность:

https://books.google.com/ngrams/graph?content=you+will+lose+weight%2C+you+will+lose+your+weight&year_start=1990&year_end=2008&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Cyou%20will%20lose%20weight%3B%2Cc0

https://www.collinsdictionary.com/dictionary/english/lose-weight-gain-put-on-weight

ок