The question of whether to fuel up before or after your workout needs to be answered with a view towards one's objective and workout type. Obviously, strength and endurance athletes pursue different goals, whereas the person predominantly interested in weight maintenance or loss has another objective altogether. This subject is worthy of a complete article in itself, so I won't go into detail here.

To your question about Fatty15 (and I'll probably be the party pooper here). I wasn't aware of the product itself, but I'm aware of the saturated fatty acid that is the product, pentadecanoic acid. The latter is a saturated fatty acid that is uniquely produced by rumen (e.g cows) microbial fermentation and that is therefore a minor constituent of dairy fats. "Minor" doesn't mean unimportant, because it is a research-accepted reliable biomarker for dairy fat intake.

Observational studies have shown a positive correlation with insulin sensitivity, and at least one in-vitro study suggests it is beneficial for insulin sensitivity in muscle tissue. The fact is, however, that we do not know whether (a) the observed correlation is indeed causal (we need RCTs for that), and (b) whether in-vitro translates to in-vivo. Now here is where I become the party pooper.

First, the Fatty15 owners/founders (couple Stephanie and Eric Venn-Watson) claim that C15:0 is an essential fatty acid. It isn't. The only essential fatty acids are the two that I mentioned in the post. That's not open to belief or interpretation; that's a fact. After all, the human body has the ability to produce C15:0 from gut microbiome-derived propionic acid (C3:0), other odd short-chain fatty acids, and also from the degradation of certain amino acids. That's why even vegans have C15:0 in their system, only not as much as regular dairy consumers.

Second, the only exuberant studies published about C15:0 have Stephanie Venn-Watson as their prime author. There is an obvious bias issue here.

But I hand it to her: her product website deserves a cum-laude in marketing.