My name is Joe and I'm a Libraphobe. (Now you all say, "Hi, Joe," and I stand and tell my story).
You may be wondering what Libraphobia is or how I came by this affliction, so let me start with some background.
One of the more difficult things to do in fitness is to measure small changes in body composition (how fat/ muscular you are). Having a trainer at your gym measure your bodyfat with calipers is a fine idea but those measurements are notoriously inaccurate. The best methods available, which probably starts with hydrostatic weighing, are too expensive or too inconvenient for most people to use on a regular basis. Which leaves most of us with two methods for assessing progress: the scale and the mirror. Neither is very good at indicating short term progress.
Scales are bad for measuring body composition changes in the short term for a couple of reasons. The first is that a scale doesn't tell you how much of your weight is fat and how much is muscle. Here's a trick question: which weighs more, five pounds of fat or five pounds of muscle? Neither, of course; they weigh the same. So if someone adds five pounds of muscle and loses five pounds of fat (which is quite possible, especially for someone new to strength training) their body composition will have changed significantly but the scale will show nothing. The scale also can't distinguish fat and muscle from water. If you retain water - which can happen due to stress (including the stress of dieting), hormonal changes, and salt intake, among other things - you can lose fat but gain water weight and all your scale will show is that you're heavier - even if your diet is actually working.
Mirrors are bad for measuring body comp changes for some similar reasons. We often can't tell puffiness caused by water retention apart from puffiness caused by fat accumulation. Remember, dieting is a stress, so hard dieting can cause water retention, which can make it seem as though fat loss has stopped when in reality you're still making progress. Mirrors are also bad because most of us aren't very good judges of physique - we might see progress where there isn't any and miss progress that is happening for a variety of complex psychological reasons. You also can't see all parts of your body equally well - sometimes you'll lose fat from around a part of you that you don't notice.
The real problems come when people look at either the mirror or the scale every day, or multiple times each day, and use the feedback they're getting to evaluate their diet or exercise program or for motivation. The problem is that any time you start to retain water for whatever reason you'll lose motivation or change your diet, thinking it's not working. The other problem is that you'll binge - pig out on food after a long period of dieting - and drop a bunch of water weight. You might look really good after that even if you put on a small amount of fat. (This, by the way, is what I think happens with cheat meals in general - they don't boost your metabolism, they reverse short term water retention caused by dieting.)
My personal problem is that I do tend to retain water when dieting, so I'll reach a point where my scale won't budge. I also seem to lose fat in uneven spurts - it will seem as if a diet isn't working, then all of a sudden I lean out. What's really happening? I have no idea, but I'm far from the only person to report results like that.
Now you see where my Libraphobia (fear of scales) comes into play. I'm not afraid of using scales to weigh food, but I am afraid to step on one. A few times in the past year I've thought I was on a good streak of eating well and exercising, and I felt I was looking better, then stepped on a scale and realized I was not as close to my target as I had hoped. That disappointment left me kind of depressed and derailed by diet and exercise plan for several weeks.
I haven't stepped on a scale now since 2009 - I am a full blown Libraphobe. At some point I'll have to do it, but I'm still afraid that if I think I've gotten pretty lean and the scale still says 180 lbs. (about 82 kg) I'm going to be really maudlin for a while.
What can one do to measure progress? Well, measuring day to day progress is almost impossible, so... don't try. Over extended periods of time - over weeks or months - your clothes should get looser (at least around the waist) and your weight should trend downwards. Weigh yourself no more than once a week, or less if you can stand it. I'm pretty sure I've gotten leaner because I can wear pants that didn't fit a year ago. Have I lost weight? I honestly don't know, but I'm pretty sure I have!
Another way to track progress include those famous near-naked pictures. Take a shot of yourself in the mirror, wearing something skimpy (or nothing at all). Every time you do it use the same clothing, lighting, etc. Over time you should get happier with what you're seeing. You may have somebody you trust look over the pictures - some of us are not good at evaluating ourselves, as psychological baggage rears its ugly head. Once again: do NOT try to track your progress on a daily basis. Too many things that don't really matter will give you the appearance of short term improvement or backtracking.