DHEA is synthesized from DHA, the most abundant Ω-3 Fatty Acid in the brain.
endocannabinoids are derived from Poly Unsaturated Fatty Acids (PUFAs) with Anandamide and 2AG coming from Ω-6 PUFAs and EPA and DHA coming from Ω-3 PUFAs. The typical Western diet is low on PUFAs and has a low Ω-3/Ω-6 ratio. Shifting the balance to a higher Ω-3 content leads to weight loss, presumably through differential activation of the endocannabinoidsystem (Watkins and Kim, 2014).
Watkins, B.A., and Kim, J. (2014). The endocannabinoid system: directing eating behavior and macronutrient metabolism. Front. Psychol. 5, 1506.