There are some things to consider when deciding how often to weigh.
1. Do not let the number on the scale define you. Your weight is just one way to measure progress. Sometimes my scale does not move, but my clothes fit more loosely.
2. Recognize that your weight will fluctuate. It is normal for weight to fluctuate 1-5 pounds in a day. Some factors affecting weight could include salt intake and normal hormonal changes.
3. Weight loss is a marathon, not a sprint. You didn't put the weight on in one day, and it won't come off in one day. Trust the process, and be patient.
4. When you weigh--whether daily, monthly, or weekly--weigh at the same time of day with a similar amount of clothing (or lack of clothing). If you weigh at the doctor's office, dress lightly each time. In her book Made to Crave, Lysa TerKeurst talked about hopping off the scale and taking off her ponytail holder and reweighing.
So, what is my answer? I weigh every morning. I use the Eat Smart Precision Scale that I reviewed here. I weigh, naked, first thing in the morning--after using the bathroom. If my number goes down, I put it in my app (Monitor Your Weight) . If my number goes up, I don't record it. Some days I log my weight every day for a week, but other days I don't log my weight for two or three weeks. But I'm okay with that. My weight varies often. But in the big picture, I've lost 132 pounds, so I don't worry about the days that reflect a 2 pound gain. I know it's temporary.
How often you weigh?