heightGroup = new ButtonGroup();
    heightGroup.add( heightA );
    heightGroup.add( heightB );
    heightGroup.add( heightC );
    heightGroup.add( heightD );
    heightGroup.add( heightE );
    . . . . .
    heightPanel = new JPanel();
    . . . . .
    heightPanel.add( heightA );
    heightPanel.add( heightB );
    heightPanel.add( heightC );
    heightPanel.add( heightD );
    heightPanel.add( heightE );

Results Panel

The remaining components are put into the resultPanel. There is no need for another button group.

  JTextField   resultText;
  JLabel       resultLabl;
  JPanel       resultPanel;
  . . .

  public IdealWeight()  
  {
    . . .
     
    // result panel
    resultText  = new JTextField(7);
    resultText.setEditable( false );   
    resultLabl  = new JLabel("Ideal Weight");
    resultPanel = new JPanel();
    resultPanel.add( resultLabl );
    resultPanel.add( resultText );
    . . .