The We Found Love hitmaker is said to be exhausted.
And according to British newspaper the Daily Mirror, the 23-year-old has been put under 24-hour surveillance and has even been given a curfew by her record label ahead of this weekend's Capital Jingle Bell Ball event.
A source told the publication: 'She's filming her Loud tour DVD in December and her team is determined that she looks, acts and performs at her best.
'They are currently in talks with Mariah Carey's trainer, Patricia Gay, to fly in and start training.'
The pop star allegedly recently had a tearful exchange with Beyonce as she hasn't been feeling well and was finding her ten-month, 101-date world tour hard.
Bey is said to have advised Rihanna to complete her tour and then take a year off.