Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Column = 3 Then 'C
If Target.Value > 50 And Target.Value <= 100 Then
MsgBox "Well done", vbExclamation
ElseIf Target.Value <= 50 Then
MsgBox "You are anorexic", vbCritical
Else
MsgBox "Have you stuck to your diet", vbQuestion
End If
End If
End Sub