Err2 - don't get too bogged down into thinking that the difference in daily weighings is all about calories... It isnt...
When we hop on the scales and see our weight - it is not just a measure of fat. We weigh the food and water in our body, the skin and bones and lean and fat... It is far from simply an image of how much fat is there or been burnt away. When I had a crazy spreadsheet on my big project and was measuring everything and tried to understand and control everything - I ended up noting all sorts of extra things like the food that I ate and their sodium content, my toilet habits, how much water I had drank, step count, exercise, medication (loads of things have sodium in), my period (ladies have an extra consideration as they retain water around then). Sodium makes you retain water so weigh heavier, drinking extra water is in your body short term but helps you release retained water.
I am skeptical that it does. In my weight loss I saw a lot of variation in how much and how fast I lost weight, but I think it had mostly to do with water retention first and maybe mass in my digestive tract second. Day to day calorie variation or level of exercise did not seem to have much effect. Long term it is the calorie reduction that causes weight loss, but much more on a long term average than day to day variations. That's what I observed anyway.
Yeah, I think sodium is a big contributor to it. I find when I eat something salty, I often wind up craving more food so the days I have higher calories tend to be higher sodium days too:
Date...................weight....BF%......Calories...Sodium
August 1, 2020.....309.8.....46.7%.....1501....
.5708
August 2, 2020.....
310.8.....45.7%.....1389.....
2881
August 3, 2020.....
311.2.....45.5%.....1370.....
3590
August 4, 2020.....310.8.....45.7%.....1213.....1884
August 5, 2020.....309.6.....45.5%.....1310.....
5075
August 6, 2020.....307.2.....46.4%.....1160.....
4703
August 7, 2020.....
309.0.....44.3%.....1557.....
7333
August 8, 2020.....
311.2.....45.0%.....1149.....
3796
August 9, 2020.....311.0.....44.5%.....1340.....
2668
August 10, 2020....310.4.....45.0%.....1427.....2253
August 11, 2020....307.4.....44.5%.....1416.....2488
August 12, 2020....306.2.....45.5%.....1427.....2267
August 13, 2020....
307.6.....45.5%.....1201.....
3508
August 14, 2020....306.8.....45.5%.....1292.....
2995
August 15, 2020....306.0.....45.7%.....1374.....
3514
August 16, 2020....305.8.....45.5%.....1329.....
3062
August 17, 2020....
305.8.....45.7%.....1305.....
4587
August 18, 2020....305.4.....44.5%.....1394.....
3374
August 19, 2020....
305.4.....45.0%.....1591.....
2967
August 20, 2020....
305.4.....45.0%.....1198.....1147
August 21, 2020....303.6.....45.0%.....1263.....1873
August 22, 2020....301.6.....43.0%.....1352.....1452
August 23, 2020....301.0.....44.3%.....1339.....1989
August 24, 2020....300.2.....45.2%.....1349.....910
August 25, 2020....299.4.....45.2%.....1250.....
3739
August 26, 2020....299.0.....45.2%.....1266.....1164
August 27, 2020....297.0.....45.0%.....1316.....
2823
August 28, 2020....298.8.....43.5%.....1310.....1429
August 29, 2020....298.0.....43.5%.....1328.....2176
August 30, 2020....296.0.....43.8%.....1395.....
2863
August 31, 2020....
296.2.....43.5%.....1358.....2289
September 1, 2020...295.0....43.5%.....1341....
3297
September 2, 2020...293.8....43.0%.....1595....
3840
September 3, 2020...
295.0....43.0%.....1529....
3820
September 4, 2020...
295.2....42.0%.....1401....
2800
September 5, 2020...293.9....43.3%.....TBD....TBD