Weighing yourself at the beginning and end of your cycle is best. Many people constantly weigh themselves while dieting (i.e., in mid cycle). This is a mistake as it can cause motivational issues due to weight gain within the cycle as a result of water retention, etc. When weighing yourself at the end of each cycle, it’s best to do so in the morning. Having a very good scale is also recommended. Everyone’s weight fluctuates on a daily basis, which leads the person to believe something is going wrong with the diet. If you start the diet on Monday, by Wednesday you can weigh 2 lbs more. By the following Monday, you can be 6 lbs less. At the end of the cycle, you may be down 6-9 lbs.
Although we each have the desire to weigh within the cycle, this will definitely cause dissolution as well as motivational issues.
In addition to weighing yourself, it is also suggested that you take your measurements as many individuals on the diet have reported loss of inches, but noticed minimal weight loss.
Following is some information that was posted by Nir (Systems Administrator) on 4/10/08, which may be helpful.
I have noticed that a number of you are frustrated that your weight is fluctuating day to day. Obviously one approach (and the one suggested in the booklet) is to only weigh yourself at the beginning and end of your cycles, and if you want to do that, good for you.
However those of you who are ignoring that advice and weighing yourself anyway, why not head over to http://www.physicsdiet.com where you can input your weight each day that you weigh yourself. You will be able to create a graph that plots your weight as it goes up and down, and the clever bit is that it work out your weighted moving average and plot it as a 'trend line'. That means your weight goes up and down but this graph shows you what your 'true weight' is. For an example, here are my data points for March and what that website made of them:
Notice how 'spikey' the data is and how smooth the trend line is!
You can have a private account, or you can share it with the world. My stuff is in kilos but the website works with pounds too.