it has a different meaning because it puts more emphasis on the author distancing themselves from what is being said. Just putting things in quotes in text may just be a value neutral quote. Writing it out is a rhetorical device because it's difficult to quote sarcastically in written form. It's basically the textual version of doing quotes with your fingers in the air. From the text:
Most of these quote-unquote marketed protein products are nothing more than glorified chocolate bars.
The “Health Halo” effect of food is when consumers believe foods that are advertised as healthier have fewer calories
That is called ‘scare quotes’, and the context is almost always sufficient to distinguish them from quotation marks, certainly in this piece they would suffice.
Most of these quote-unquote marketed protein products are nothing more than glorified chocolate bars.
The “Health Halo” effect of food is when consumers believe foods that are advertised as healthier have fewer calories