I think that science has barely scratched the surface of what we know about metabolism. And, by metabolism, I refer to how our bodies process energy, not the rate at which we burn it.
As I get older - and arguably in better "shape" than I've ever been in my life - I find myself quite sensitive to various foods when it comes to utilizing them for energy. As a youth, I could eat whatever. But, now that I'm older, if I'm not eating leafy greens, vegetables and a lot of different proteins (eggs, cheese, yogurt, milk, poultry, beef, fish, nuts/beans/grains etc) then performance in the gym, on the erg, it all suffers.
It could very well be all in my head, but I am someone who has struggled with controlling my weight ...since I was a baby, really. 35#'s after 1 year old!
I couldn't even sit up-right without assistance. Fortunately, they put me on a diet of sorts, and I stayed at 35# until I was 3 or 4. Still, I remember being 110#'s in 5th grade, and pretty much put on weight regularly until I was 200# in 12th grade, and really packed it on in college and beyond.
It has only been since I started drinking Kombucha that I've been able to lose weight and keep it under control. Now, that could be all in my head, with a series of circumstantial anecdotes, but I do believe that the shift in my diet from any old thing to mostly organic foods, and refusing to take in refined carbs until I met my weight goal, and then only on weekends on a limited basis.
I could literally write pages of various conclusions of various studies I've read regarding the evils of Sucralose and other artificial sweeteners and their impact on insulin and the microbiome. But, it's a deep internet rabbit hole, and there are smarter people than me to break it down in a more clear fashion than I can.
To speak about somebody elses ability to take in various fats ...I can't say. I do think our genetic predispositions have a lot to do with how our bodies handle those foods. I could of course, be wrong. I would just introduce them one at a time, in moderate amounts and assess your performance, and how you feel one hour after consumption, and the next day's energy level and resting heart rate, to see if it spikes. Although I'm not allergic to peanuts, when I have peanut butter, my resting heart rate spikes that night by about 5-7 bpm, and my HRV takes a nose dive. It could certainly be something else - but that's the only thing I think it can be. So, if I have something important to do, I avoid it the previous day. Which is a shame, because I rather like it!