7-oxodehydroepiandrosterone (7-oxo DHEA and more commonly known as the brand name 7-keto) is one of three oxygenated metabolites of dehydroepiandrosterone, and these three oxygenated metabolites interconvert with one another but do not convert back into parent DHEA; 7-keto supplementation is a way to get these three oxygenated metabolites without using DHEA supplementation, and DHEA may form androgenic and estrogenic hormones via an alternate metabolic pathway (which 7-keto does not participate in).
7-keto supplementation is mostly known to not be hormonal; it can interact with steroid metabolism but the exact manner in which it does it not fully elucidated. It does appear to have anti-cortisol mechanisms as the enzymes that activate cortisol (from the relatively inactive precursors of cortisone and corticosterone) are the same that interconvert these oxygenated metabolites. Although it appears to be anti-cortisol by its mechanisms, there is insufficient evidence to support these mechanisms in the body following oral supplementation.
Studies using 7-keto supplementation tend to note an increased metabolic rate later on during a caloric restriction period (which is secondary to reducing the rate of metabolic rate decline associated with dieting, and becoming a relative increase) although the quantity of data on this is pretty minimal if we exclude studies with possible conflicts of interest or those that use 7-keto alongside a multitude of supplements.
7-keto appears to be a somewhat promising non-hormonal fat burning agent but requires more evidence on both of those claims.