CRJ-200 pilot reported fuel system malfunction resulting in unexplained fuel loss during cruise. Flight crew diverted and landed uneventfully.

Narrative

Departing from ZZZ to ZZZ1 with fuel well above Minimum Takeoff Fuel; and MELs that include ANTI-SKID INOP; and reached 2nd fix 'FOD' (Fuel Over Destination) with fuel as planned. MEL required longer runway than usual; as planned and considered prior to departure. Before descending; updated landing fuel weight decreased in a relatively rapid rate as updated and monitored by flightdeck crew. After discussion; a fuel leakage brought up and considered as one of mechanical irregularity or failures that might cause the undesirable trend and as threat to plane; passengers and crew.As the undesirable trend continued rapidly; ZZZ1 landing fuel showed 1;550lb; and crew declared Minimum fuel; and later on [requested priority handling] due to the condition of being concerned about safety as a potential distress condition that required an immediate decision and action; and under the circumstances considered necessary.Because of ZZZ2 as relatively less crowded airspace than ZZZ1; and due to the MEL requirement and relatively safe amount of fuel for landing; ZZZ2 was chosen as the closets suitable airport for landing and was requested as a diversion destination by ATC.The crew complied with all controllers' clearances without any deviation of any rules; instructions or regulations; and safely landed at Runway XX according to MEL requirements. Throughout the flight CRM/TEM (Threat and Error Management) were maintained and model was utilized; while the FA (Flight Attendant); Passenger; Dispatcher; controllers; and later Maintenance Operations Manager; were notified and / or discussed with.Cause: FMS showed rapid trend of low fuel for landingSuggestions: Considering MELs in fuel planning