Quoted from the article:
"Equally important are the variables of relative dose and duration of use. The rats in the study (there were actually two studies) were administered doses ranging from 5-80 mg/kg of bodyweight, per day With Wistar rats (the type of rat used in the study) usually weighing 1 pound or less, the following figures will be based on a rat weight of ½ kg (slightly over 1 lb). Using that figure, the rats were given a dose of GW ranging from 2.5-40 mg daily. Applying those same dosing guidelines to humans, an equivalent dose for a 100 kg male would be 500-8,000 mg per day. Most bodybuilders only use 5-20 mg/day, meaning the rat dose was 25-160X higher than what is normally used in humans."
They study standardises the dosage to mg/kg, meaning the rats didn't receive 5mg-80mg. So he did multiple by .5 to get the actual dose given to those fat af rat's LOL (however that figure is pretty irrelevant). He did not do the surface area conversion between rats and humans of roughly 6.2. So in reality the correct HED for a 100kg human is 80mg - 1290mg.