Agreeing with @Parsifal here.
Weight management is definitely not a simple matter of calories. It has to do with all kinds of things including toxins which get sequestered within fat cells.
Also different people metabolize fats, sugars, carbs, protein etc slightly differently. Me personally, when I was younger at least, I had a genetic or situational problem which caused me to not metabolize carbs properly, especially simple sugars. They would break down into alcohol, then into acetyl-aldehyde, and then the acetylaldehyde would not be metabolized or break down properly into a form thjat could be excreted from the body. This meant physical problems like clumsiness while the toxins were being eliminated.
Also, not all weight is fat. Some of it is going to be cr-p stored in the large and small intestines which haven’t been eliminated because its stuck to the intestinal walls and hasn’t been moved to the rectum yet.
People like to think that obesity is all about fat. It’s not. There are all sorts of digestive issues that can be contributing to weight problems.