I just want to know if I can take MCT oil while fasting and if it will break my fast but I think it will because it’s over 100 calories?
Fasting and Intermittent Fasting represent actual fasting of course, which leads to an increase in beneficial ketone bodies (KBs).
Consuming MCTs represents “metabolic fasting” or “fasting mimicry” in that some of the same metabolic markers increased with actual fasting will occur; this includes beneficial KBs.
Moreover, since actual fasting under some conditions will lead to proteolysis (breakdown of proteins in muscles), and MCTs are known to spare such proteolysis, this is another benefit of consuming these ketogenic aids while fasting. This should not happen with shorter duration intermittent fasting (IF).
Taking ketogenic aids would of course make the actual fasting easier because your brain and other tissues would have an energy source.
On the contrary, if the purpose of the fast is to put your body in negative energy balance (more energy utilized than that coming in via diet), rather than purported “cleansing” benefits, then providing energy in the form of MCTs could lead to less fat loss. I would not say taking MCTs "breaks" the fast.
So, in the end it is a balancing act. With MCTs, the fast or IF is more functional and doable.