Here's an interesting tidbit I found while reading an article on AOL Body this morning:
Weekly weigh-ins are a staple of many popular diet programs, but studies now show that daily weighing is the key to lasting loss. When researchers at the University of Minnesota monitored the scale habits of 1,800 dieting adults, they found that those who stepped on every day lost an average of 12 pounds over 2 years (weekly scale watchers lost only 6) and were less likely to regain lost weight. The reason: "The more often you monitor your results, the quicker you can catch the behavioral slip that causes weight gain," says Jakicic.
This idea has been cropping up a lot lately, but it is the first time I've seen a study cited. Other accounts I've read have been anecdotal. Until recently, conventional wisdom has suggested that weighing weekly was a better option because our weight fluctuates several times a day. Supposedly this means that weighing daily is useless because a higher number between yesterday and today could just mean you drank too much water or something.
Personally, I think whether you weigh daily or weekly depends on your temperament. Some people have obsessive personalities and weighing daily would drive them crazy. I know that one of the things they tell people in eating disorder programs is not to weigh daily. On the other hand, I know that if I weigh myself and I like what I see on the scale, I am more mindful of my food and activity choices for the day because I don't want to mess up that good number. Perhaps if I weighed more often, I would be motivated to exercise more often.