Answer: Because Sweet Nothings is an expository piece of writing.
Step-by-step explanation:
Kowalski, the author of Sweet Nothings presents evidence to support weight loss and refute weight loss because her writing is an expository piece of writing.
An expository piece of writing just as the name implies is one that exposes readers to a particular idea or topic. It’s purpose is to inform about and describe a particular subject or idea.
Kowalski, the author of Sweet Nothings may have been expected to stick to a particular side of the subject, that is either present evidence that supports weight loss or the one that refutes weight loss.
Instead, she presented both because her writing is an expository piece informing her readers about the both the advantages and disadvantages of weight loss.