Jussie Smollett Fasting in Cook County Jail, Only Drinking Water

Jussie Smollett is taking Lent very seriously this year, choosing to give up food while behind bars ... and he's intending to stick to it for nearly 5 more weeks.

Sources with direct knowledge tell TMZ ... Jussie's fasting for spiritual reasons and hasn't eaten anything since Lent started on March 3, a full week before he started serving his sentence in Cook County Jail -- and he's continued the fast behind bars.

We're told all he's ingested is water, and while his plan is to keep that up until Lent ends on April 17, Easter Sunday ... he's taking things "one day at a time."

Our sources say Jussie remains in good spirits, noting this is not a hunger strike or protest to his imprisonment. Remember, Jussie made a point to repeatedly say, during his sentencing, he is not suicidal.

He's nearly 2 weeks into the fast, and we're told he's still physically okay and in "good spirits." Cook Co. Sheriff's Office says it can't comment on religious or spiritual practices of individuals, but did say jail staff monitors all inmates to "ensure their health and wellness."

On Wednesday, his brother, Jocqui said Jussie had been moved out of the psych ward thanks to fan support, with #FreeJussie circulating online.

While he claimed his brother was kept in a restrained bed during his time in the ward, a rep for the sheriff's office says that wasn't the case and denied Jussie's bed had any restraints.

We're also told he was moved out of the ward because health services needed space for another detained person, and the decision to move him was made by medical professionals.