Eating dehydrates you faster. I doubt he ate much especially if he had no water. He could have gone without food for 5 days easily.

Though termites do go a long way food wise. There's mearly double the calories per gram in termites than in a good steak...and more protein too. A quick google search came up with a figure of about 550 calories for 100g of termites...pretty good though that's a LOT of termites!

I don't recall how protein ranks on the 'water used to digest' scale but I'm sure it's better than carbs.