I had panic attacks years back. They're probably the most terrifying feeling I ever experienced. Benzos fixed them immediately (the underlying feeling remained, but I never went into a full-fledged attack after I started the pills), and I used the time they afforded me to fix my health by dieting and exercising. Those things helped me get over the panic attacks and I know a friend who had GAD who was also cured by following a healthy diet and exercising, so I recommend these things whenever I can. Unlike other interventions, they don't mess with your mind, they're not victim-blaming by telling you to change your ways of thinking: they just tell you, do this practical thing, and you'll see results.

Caffeine had the exact same effect on me. And sugary drinks sometimes. My idea is it had something to do with adrenaline. My experience definitely contradicts the results of the research you mention.