Every Sunday you cook several pounds of chicken, countless carrots, and steamed broccoli. You rice cauliflower to avoid carbs. You select yogurt with low calories and sugar to complement your diet. Then you carefully package a week’s worth of lunches for you (and probably others in your family) to help keep everyone’s healthy eating on track. A new study, however, reveals your hard work can be completely undone by the free food given out at work during the week.