My observations are only for the part between SC and CTA. At Manthralayam road, you can get tea/coffee. At GTL, where the train halts for around 20 minutes, you can get Samosa, Masala wada, Bread Omelette, Idli Vada. You can even walk into the Veg refreshment room, and have hot breakfast, as the train halts for ample time. MRP written on the water bottles is Rs 15/-, howver the guy will demand Rs 20/- Avoid paying him Rs 5/- extra, and if he insists, report him to the station authorities, or tweet @RailminIndia, @DRMGTL, quoting your PNR number.
Post GTL, at Bellary, you will get some food stuff. After that, the landscape gets pretty dreary. At Molakamalamuru, you can get some puffed...
more... rice and coffee and masala wada. Lunch orders are taken, and food gets loaded at Chitradurga.