Thanks! I Adapted this into this and it works perfectly:
{{if $member->inGroup(48) or $member->inGroup(49)}}
<style>
body {
background: url({{foreach $sidebarFields as $group => $fields}}
{{foreach $fields as $field => $value}}
{{if $field != "core_pfield_6"}}
{{else}}
{$value|raw}
{{endif}}
{{endforeach}}
{{endforeach}}) no-repeat left center fixed;
-webkit-background-size: contain;
-moz-background-size: contain;
-o-background-size: contain;
background-size: cover;
background-color: #22252A;
}
</style>
{{endif}}
(The New If makes sure the Loop only outputs the URL Field)