No. Only works on halved avocados, not crushed or sliced.
Avocado trees emit a hormone that stops the fruit from ripening on the tree, which is why they seem to go off really quickly in stores or at home. Riper avocados actually have less sugar in the flesh - try a fimer one next to a softer one and see which is sweeter.
Lemon juice on a cut surface will help slow the browing which is a reaction to exposure to air, but only suggest do this for a few minutes - and it alters the flavour of course. . . .
And avocados have more fibre than brown bread, more Vit E than almost any other fruit, the same sort of fat/oil as in olive oil i.e.essential fatty acids, they are a good source of Vit B6, and are full of anti-oxidants - so keep munching on them all you want!