How often a person steps on the scale depends on his or her goals, says Dr. Schwartz, director of the Rudd Center for Food Policy and Obesity at the University of Connecticut.  Once a week is the most common recommendation in the obesity treatment arena, however anorexia and bulimia patients should avoid frequent weighing so they won’t fixate on minor fluctuations.  “For those who are just maintaining their weight, once a week is fine to give you a good average weight.”  Wednesday is the best day for weighing, because it is furthest from the weekend when restaurant dining and chaotic eating are more common, she says.  For someone trying to lose weight, weighing three times a week or more makes sense.  “It allows you to really understand what’s happening in real time,” Dr. Schwartz says.  The best time to do a weigh-in is soon after waking, when weight is most consistent.  “You have to be careful not to let those little change on the scale be blown out of proportion,” she says.  “But you also don’t want to go a month without weighing and then see you’ve put on 15 pounds.  If you have a bad weigh-in and that ruins your day, then that’s a sign to stop such repeated checks,” she says.  The number on a scale is just on piece of information people should use to guide behavior.  (The Wall Street Journal/Heidi Mitchell)