From her website:
Consumer Reports recently made headlines with a new study showing high levels of lead in many protein powders and shakes. The average amount of lead detected had increased from a previous study done 15 years ago. It’s ironic that this particular wellness fad, like many others, may actually be compromising people’s health.
Ultimately, this cartoon is about more than just one scientific finding. If we look at what happened with COVID, or childhood vaccinations, or even climate change or January 6, we can see how easily conventional wisdom gets turned on its head by bad faith actors, especially in a media environment lacking responsible editors.
I mean, having participated in this, there's a reason and motive behind it : you need increased protein to maintain muscle mass while losing weight. There are some manners of dieting which includes being careful with your macronutrients (proportion of carbs, fats and proteins), and if you're decreasing your calories ingested, it becomes more and more challenging to feel full, get adequate protein and not go over your calorie limit.
Plus, the point in the comic is the lead is bad, not the ingestion of protein, which has nothing to do with the "fad"
That's doubly true for people with vegan or even vegetarian diets. There are a lot of vegetable protein sources, but not many are convenient if you're counting calories and want something low-cal and relatively cheap to replace a meal without much effort.
Also, it's weird to call it a fad. I remember seeing infomercials for protein shakes and pyramid schemes involving them since I was a kid.
I think it's because people are doing it randomly, or that it's less a specialised product and being further adapted by mainstream brands and shops. I don't think it's a fad, but I'm trying to just communicate with that guy