Answer:
Question 2:
Juan y Raúl no han adelgazado or bajado/disminuido de peso porque no hacen ejercicio.
(This sentence denies that Juan and Raúl have lost weight so the answers are: they have not lost weight - lost.)
Question 3:
Pero María y yo no hemos comido or no comemos porque trabajamos en exceso y nos olvidamos de comer
(Since Maria and the other person work excessively, they forget to eat; so the answers are also related to not eating)