Skinks refusing dog food

[Y33T]

For a while now my skinks Kirra and Bajo hasn’t touched their dog food at all, they will eat other things like snails. I assumed it’s seasonal behaviour but wouldn’t it be over by now? In case they’re just bored of dog food what should I feed them instead? Should I try raw dog food?

Both their basking temps are in low/mid 40s (Celsius). They are offered food once a week and I try to give them tons of variety. They get different flavours and brands of dog food every week. Their enclosures used to be facing eachother but I recently moved them side by side so they don’t see eachother so hopefully it does something.

They are losing some weight obviously not dangerously quickly so far, I haven’t weighed them yet. I know Kirra was slightly overweight and often struggled to squeeze his butt into his log but now he’s slim enough to fit without any struggle. They are still very active and alert I assume the weight loss is due to them getting plenty of exercise and little to do with their lack of appetite.
When does it become a problem that I may need to see a vet?