Not necessarily I've eatten it on a full stomach and the effects were less prominent but slightly longer lasting, imo. Though the effects will have a faster onset if consumed on an empty stomach. If your a novice/low tolerance to opiates ingesting it on an empty stomach may not be the best idea as it may create some powerful and possible debilitating nausea in the same way mu-opioids do if dosed too high. Don't buy it in any sort of pill form or extract as it is usually less economical than just buying the powdered leaf. The active chemicals theorized in kratom are mitragynine and 7-hydroxymitragynine which I had read effect the Delta-opioid receptors more than the Mu but wikipedia now says other wise (its wikipedia so take this information with a *pinch* of salt). It produces standard natural and synthetic opiate (i.e. oxycodone, morphine, hydrocodone, coedine, ect.) effects with a little less euphoria and more focus on the physical aspect of the high imo. Definitely something worth trying while it is still legally available I believe . Many people enjoy every aspect of it other than having to consume the nasty texture and taste of the powder, though that can easily be masked by gulping it down with an acidic drink such as OJ or Sunny D. Oh and you may not feel the effects of it the first couple of times after ingesting it as it is a structurally complicated chemical (similar to yohimbe alkaloids and tryptamines but acts on the opioid receptors) so your body may have trouble deciding exactly where to transmit its actions.