I think it may depend on other factors than just intake and caloric use.
People can have endocrine and all sorts of other problems that make them sensitive to various foods and unable to process them as others do.
Basically no one can make body mass out of air. So, patients extra weight could be due to too much fluid, but that would show up with measurement of electrolytes and other components of blood. Examination of patient would show edematous areas of excess fluid. Like in the feet, shins, lower back. Most times, that is difficult to see while person is morbidly obese. While in hospital, measurements of fluid intake and output and weight gain or loss with a controlled diet would help in diagnosis. Giving patient diuretic could help remove excess fluid.
If your relationship doesn’t describe their experiences while at the doctors my guess is that that person is a poor historian. Seeing 20 doctors as you report is an indicator of that the patient is not benefitting from professional help, and maybe looking for a diagnosis.
First step. Control food and fluid intake. Second step. Review all medical diagnostic tests with a consultant physician who will explain why the diagnosis is as it is. Maybe even suggest new tests. 3rd step: consider that patient cannot understand their condition, or is in denial, or has a behavioural problem.
I know 3 people who are morbidly obese. One is a cardiac nurse. None of them think that food intake is a problem with them....you ever wonder why in times of famine there are no obese people walking around? You ever see some guy sitting under a tree rolling around in fat, telling an interviewer, “I can’t figure it out, I only eat a stalk of celery and a bug per day, and I still am obese while everyone else is a walking skeleton”? Endocrine excuses only go so far. Endocrine disorders like hypothyroidism would show other physical symptoms. Good luck. It is very difficult to treat morbidly obese. If they have a code blue , intravenous drugs cannot be given cause there is no way to isolate a vein without a “cut down” and that can take too long in an emergency situation. Intratracheal administration of drugs is not reliable.
Cold fact to consider: How many morbidly obese people do you see walking around , without a medical condition, over 60 years old?
“People can have endocrine and all sorts of other problems that make them sensitive to various foods and unable to process them as others do.”
Which affects their ability to burn calories. The rate at which we burn calories varies by individual...and can vary in the same individual due to internal and external factors.
That’s why it’s necessary to adjust your intake.