Ah the weigh in. When a weeks worth of dedication (or lack there of) all comes down to single moment of truth. How receptive your client is in receiving their weight is on them. Some have been taught to take the ugly truth head on while others avoid it like the plague, even when they have followed the responsibilities set forth. Either way, the results hold a lot of weight ;) It is your responsibility to take the necessary measurements regardless of how it will affect their mental or emotional state. This requires tact that is all about creating positive momentum moving forward. So what is the optimal time to get your client on the scale? Before or after the session?
A good number of my clients arrive to our sessions with emotional baggage. They have either had a really long, arduous day at work, or they are going through some issues in their personal life. Some are even close to cancelling the session all together prior to arriving. Not a wise time to throw them on the scale. In the event that the results are undesired, the client is then forced to process those results while they are working out with you. This isn't a problem if the results are good though, as it will motivate them to kick even more ass during the session. But on the off chance that they have had a set back, nothing can feel more defeating. Instead of focusing on the task at hand, you're then obliged to do damage control, paving the way for an ineffective workout to say the least.
As you know, sometimes just having an open ear can do wonders for a client that is in need of a solid vent. But more often than not exercise can serve the same purpose and do so more effectively. Allowing your client to decompress through the hard workout that you setup will provide the softest cushion to facing the music, good or bad. You are essentially setting them up with the best emotional state possible to receive news about their progress. So, for this reason it is generally best to weigh your client after the workout. Just make sure to set some time aside to discuss the results if necessary.