No way would the LAW be able to properly enforce her policies if Yukari were to fatten her up a buffet's worth of weight, now would she? Like, can you imagine Eiki trying to chase after Yukari for screwing around with the population's weights, only to make a massive dip in her flight path due to "someone" suddenly tossing an extra 15 pounds onto her own formerly slender frame? Eiki would be horrified to find a newly plush gut under her extra-small clothing. Knowing Yukari, she wouldn't be content with doing this just once- she needs the fuzz off of her tail for good. Every time Yukari would pass a well-endowed human, the weight would be transferred from them directly into Eiki, completely throwing off any chance of pursuit. She'd soon land with a "thud" onto the ground, her entire body wobbling because of the impact- now sporting a much more bottom-heavy figure than before. If one were to follow behind her when she crashed, they'd see Eiki's well-endowed rear end on almost full display, being shielded by an skirt with a pair of overstretched underwear beneath, clamping on her lovehandles like a vice, squeezing the surrounding area outwards by the slightest distance. After all, her buttocks was twice as wide now than it was before Yukari began her all-out assault on Eiki's mass. Even the most well-crafted pair of panties would struggle against such a sudden force.
Or maybe Eiki would catch up to Yukari with ease and smack her around with the Rod of Remorse for a little while. Not like I know the air speed of a 17 year old girl nor the judge of hell.