That isn't what it says they're claiming at all. "this imposes a practical and financial strain on the scalability" is just a way of saying that it gets more expensive for bigger people.

They did the study in part to determine if it's actually necessary to scale up for people whose additional size is mostly fat, or if they can take the same (smaller, cheaper) dose as someone who is their height but has less body fat.

It's explained in the source paper:

> Background:

> Psilocybin is a serotonin type 2A (5-HT2A) receptor agonist and naturally occurring psychedelic. 5-HT2A receptor density is known to be associated with body mass index (BMI), however, the impact of this on psilocybin therapy has not been explored. While body weight-adjusted dosing is widely used, this imposes a practical and financial strain on the scalability of psychedelic therapy. This gap between evidence and practice is caused by the absence of studies clarifying the relationship between BMI, the acute psychedelic experience and long-term psychological outcomes.