By all means, have the discussion! My daughter has overweight/obese friends that have NO CLUE how to lose weight. They will sit there eating candy (fat free!) And ask me how she can eat so much and stay so thin. (She is 5'8" 110lbs, a lean mean dancing machine that just got the first perfect physical fitness scores on her drill team's summer athletic tests) And she is truly always eating. I point out that she rarely drinks soda, snacks on meat, cheese and berries all day and stays away from carbs naturally. These girls are miserable about their appearances. It breaks my heart that their mothers take them to Jenny Craig or Weight Watchers. And they never learn. Your kids have the advantage of a mother who knows better! Let them benefit from that!