I weigh every morning, sometimes during the day and every evening before bed! I don't get disheartened at small gains and I know I will weigh 2, 3 or even sometimes 4lbs heavier at night depending on what I have eaten during the day.
Here's the science behind why several times daily weighing is not a good idea. They key part of what you said here was 'depending on what I have eaten during the day'. Because - the food we eat and have in our body at any one time plays an important part in what our weight will show on the scales. When we're talking, actually, about these relatively small masses of weight (1-4lb): the food we are carrying in our stomach, bowel etc have a part to play in what we weigh.
But the food we are carrying at any given time does not tell us what we will end up weighing. For example, potatoes are very heavy to carry around. Whereas marshmellows are very light. But if you ate the same weight of potatoes in marshmellows, you'd gain a lot more weight than the potatoes!
Or another way of putting it: what ends up being fat has no bearing on its weight before or a day or so after you've eaten it.
{NB - this is actually part of the science behind how Slimming World works. You'll notice that a load of the free foods are 'dense' like potatoes, pasta, fruit, veg meat etc whereas syn foods are quite 'light'. The free foods are naturally filling because they are heavy. For the amount of calories, fat, weight they contain, the free foods are largely 'heavy' ie naturally filling.
So you feel full even though what you are eating is not likely to turn into fat itself. Thereby allowing your body to enter its natural fat stores when it needs energy (for exercise or just for keeping your body ticking along): burning the fat and loosing the weight.
It's more complex than that because of glycogen in the first week or so, but basically that's the science behind long term success of Slimming World: fill yourself up with heavy foods that are low in calories and your body won't have enough calories to cope because you'll be too full to eat anymore. Your body will then enter your fat stores for energy.
There are always exceptions and some things are there to make the journey easier for us (eg Muller Lights!) but largely you'll find the above is true.}
With weighing to establish the changes in your body, sticking to a regular routine (ie always weighing on the same day of the week, after a normal lunch or weighing before you wake etc), along with allowing for standard daily fluctuations is the *only* way to know what is going on in your body.
My advice: if you really have you weigh yourself daily, always do it in the morning so at least you can see what's going on, get some decent scales and accept that some days you will show a gain and not be able to work out why. It'll average out.
