The Coconut Diet doesn’t cause weight loss. The idea came up because coconut has an oil made up of more than half its fats with 8 to 12 carbons. These fats enter the energy factories of the cells in your body more easily than other fats like corn oil which have fatty acids with 16 or more carbons. The idea was that more fat would be burned than stored compared to other fats. Studies failed to show a benefit for weight loss except for one small study in Brazil which compared coconut oil to corn oil. Saturated fats are not as well absorbed as corn oil so this was not a fair comparison.
Learn more about diet myths at https://www.uclahealth.org/clinicalnutrition/nutrition-fact-or-fiction