They do regular health check-ins with the contestants, and if you’re not losing weight but there’s no footage of you catching food, they’re going to figure out pretty quickly that something’s up.
On top of that, the locations are chosen so that just hiking out to you with food would be a survival challenge in itself - and coming in by boat would almost certainly be noticed.
Interestingly, I've just been binge watching the show for the first time. I'm on season 5 currently.
I've put things in my ass for no points. 1000 points sure sounds worth it.