I understand the purpose of this chapter but the context is all wrong.
If you come from a world of magic, then of course you know for a fact that instant results are possible because of magic.
Second, why wouldn't Oka go to the magic users of her friend group to help her out? Dark Elf, Styr even the Skeleton might know a magic formula to burn off body fat.
Last but not least the final picture is wrong. Most of the exercises that he used in the past were made possible but without some of those gadgets.
Weights you can use, jump rope too, massage devices too.
What he is actually afraid of is to endorse these devices because people would rather do one payment for a device they can use at home then pay every week for an appointment with him.