or just do a moving average over some days. Works better.
And water weight, fecal residues, etc vary so much day by day. Were yours so constant insofar to be able to track it accurately to the grams?
At the time I have studied a lot the existing medical literature, and this was the recommended rate, so I have adjusted the diet so that the weight loss per day would oscillate around 140 g per day.
The weight must be measured every day in the same physiological conditions, i.e. in the same order relationship with respect to the various activities that modify the weight, like eating, drinking or eliminating their products.
A good moment would be in the morning, immediately after waking up and relieving yourself.
If one would eat in the evenings wildly varying amounts of food, then the weight in the morning could be affected by a noise due to variable amounts of food that is not completely digested yet. However that would not happen when one is eating a calorie-restricted diet for losing weight, when one would have to eat about the same minimal amount of food every day, which would be quickly digested.
While I was losing weight, I could see very well every day its evolution to the grams, and the effect of any change in the diet. Sometimes I succumbed to the temptation of eating like before starting to lose weight, and after such days I gained weight in a day almost as much as I was losing in a week, which increased the time until reaching the target weight.
I eat the same stuff every day, weighing myself after going to the bathroom, etc, yet my weight easily varies at least 500 g from one day to the other. And if I eat just a little bit more carbs in a weekend, then well, it's like 2 kg of extra water weight on Monday.
I have lost weight (from around 120 kg to around 76 kg) about 15 years ago.
Nevertheless, I believe that if care is taken so that the calorie-restricted diet still includes a normal amount of all nutrients except carbohydrates and non-essential fat, 4 kg per month, like I did, should not cause any health problems.
Unfortunately, I have seen too many suggestions about how to lose weight that do not pay enough attention to provide all nutrients. Such diets can be sustained for a few weeks, but not for longer durations, like a year or more, which are needed when the required weight loss is great.
My weight can vary from day to day exactly as much as yours, but nowadays it rarely does.
The main difference between how I eat now and how I was eating before losing weight is that previously I was eating until feeling sated, but now I always decide how much to eat before starting to eat, so for most days the energy intake is similar, so the weight oscillations are small. When I happen to eat a more copious meal, I compensate the next day, mainly by cutting the carbohydrates during that day.
Only either the carbohydrates or the (non-essential) fats or both must be reduced. It does not matter which of them is reduced, as long as the total calorie amount is restricted enough. It may matter only due to personal preferences, which may make one variant or the other easier to support.
One must use some digital scales for measuring the weight every day at precisely the same moment, because the weight varies during a day by much more than the difference between 2 successive days. An appropriate rate of losing weight is between 100 grams and 200 grams per day, e.g. about 1 kg per week. If the measurements show another rate, then the amount of daily food must be increased or decreased until the rate is in range.
Regardless with which diet you start, if you adjust the amount of carbohydrates and fat according to the daily weight measurements, in a week or so you will converge to the right amount of daily food. However, this requires to measure by mass or by volume all the food eaten. Those who do not succeed to lose weight fail because they either do not measure what they eat or they cannot abstain from eating more than what they have planned to eat.
Losing the weight is the easier part. More important is to plan a diet for after reaching the target weight, a diet that will keep the weight constant, i.e. which must still be calorie-restricted, but at a normal level, and which must be appealing enough, so that one would never be tempted to eat again in the way that caused the overweight in the beginning.