Sam Asghari has branded Britney Spears as ''authentic, funny and humble'' as he hit back at a troll who branded her social media ''scary''.

The 'Toxic' hitmaker's boyfriend heaped praise on the singer as he defended her against an online troll, who slammed her Instagram posts.

Responding to a comment where Britney was branded ''scary'', he replied: ''what's so scary about being the biggest superstar in the world being herself (authentic, funny, humble) without caring what others think ... we need more people like her and less Karen's. also instagram installed this button that you can hit to unfollow about 10 years ago (sic)''

Meanwhile, Sam previously revealed he wants to marry Britney.

The 26-year-old personal trainer - who has been dating the 38-year-old singer since 2016 - confessed: ''I think that's the whole point of being in a relationship - otherwise why would you be in the relationship?''

To cope with the attention that dating the 'Gimme More' hitmaker brings, Sam turns to the gym to refocus his energy.

He said: ''I use training not for the physical factor, but for the mental factor. I go to the gym for spiritual things and confidence. I use my fitness lifestyle as something to help me with everything else - my career, my relationship, everything I do. I built confidence, discipline and everything from the gym ... That's the best thing - if you share that same passion you can go out and have fun and exercise together.

''I've done the workouts with her many times. We actually did a video last year. A lot of the workouts are on my website.''