The 23-year-old has been used sparingly since seeing a move to Tottenham Hotspur break down in 2015, featuring just four times in the Premier League so far this season.
Berhaino's last appearance for the Baggies came in the 1-0 defeat to Bournemouth nearly two months ago, with Pulis admitting last week that the England international hopeful is still lacking the fitness required to nail down a place in the squad.
Having already been put on a weight-loss programme last month, Berahino is now in France working with Pulis's former colleague, who will attempt to get the striker back in shape in time for West Brom's meeting with Burnley after the international break.
"Saido's off at a fitness centre working with a fellow I worked with when I was young in management," he is quoted as saying by Sky Sports News. "He's got a week to top himself up to a level and hopefully he'll be not only sharp but at a level to sustain it.
"He'll assess what we've done and make a judgement on what Saido needs to do. We think this is the best way. It will be a good experience for Saido and for the club so we'll get a good idea of his conditioning."
Berahino started 17 times for Albion last season in the Premier League, scoring four goals in all.