Discussion: For example, two twin brothers eat the same calories but in different compositions. Will they necessarily gain the same amount of calories?

Surprisingly! Processed foods are making us gain weight much faster than the same calories of natural foods. The nutrients we eat and drink and the calories they carry cannot vanish, but they can be redirected to other non-energy, "non-countable." purposes.

The energy in food and beverages available for the body's use is not fixed or uniform for everyone due to absorption and routing differences.

Since the routing of food between the two primary uses (tissue building and maintenance, as opposed to available energy and fat accumulation) is not fixed and differs from person to person, summing the calories in food and beverages as we do today is inaccurate.

Link: Calories cannot disappear but can be redirected as uncounted.
https://www.sf-healing.com/page/141 (Copy & Paste)