Angular 2+ wait for method / observable to complete

I need to check te back-end for authentication status, however te code completes before te observable return is finished. Which would result in an undifined.

canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
    this.isAuthenticated();        
    return this.authenticated; 
}

isAuthenticated(){
    this.loginService.isAuthenticated()
        .subscribe(status => this.authenticated = status)
} 

How would i change this code so i wait for the observable to complete to get the authenticated status before the code returns.

Note: the Angular canActivate method does not allow me to write the code as shown below:

canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
    this.loginService.isAuthenticated()
        .subscribe(status => {
            this.authenticated = status;
            return this.authenticated;
        });
}

This results in the followin error:

Class 'AuthGuard' incorrectly implements interface 'CanActivate'.
Types of property 'canActivate' are incompatible. Type '(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) => void' is not assignable to type '(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) => boolean | Observable | Pr...'. Type 'void' is not assignable to type 'boolean | Observable | Promise'.

A suggestion for a solution for this error would also be helpful.