Few people would force themselves to eat for a week on a $25 budget, with only basic ingredients allowed, no existing pantry supplies permitted either and no taking freebies from others, which is what I just did for Mastercheap Raw. But while the process might be extreme, everyone can learn something from the experience and plan their food shopping budgets better.

I'm seated at a media launch at Otto Ristorante, one of Sydney's more exclusive restaurants. Options on the menu include eye fillet of Angus reserve beef and red wine rigatoni with a pork sausage ragu and buffalo ricotta. It's all utterly tempting, and that's before the waiter recites the specials. But I'm not paying attention, because I can't eat any of it. Those are the rules for Mastercheap Raw.

There are only 17 items on the $25 Mastercheap Raw shopping list, so in a sense every one of them is a "hero ingredient": take one out and the whole week would instantly look a lot bleaker. But if I had to pick a single vital element that shows up in almost every meal, it would be the humble container of table spread (that's margarine to most of us).

When I first did Mastercheap back in 2010, when people asked me "How are you coping? Are you hungry all the time?" I could honestly answer "Really well" and "No". If I got asked those questions right now during Mastercheap Raw, I would have to prevaricate slightly. And the reason is mostly carbs.

Day 4 of Mastercheap Raw. Past the halfway point. This can't be called suffering. I'm eating three meals a day and getting plenty of vegetables and protein. But at this stage, the notion that "doing it yourself" delivers better results is not convincing. For that to be true, you need a bigger budget. And one thing I'm learning in this experiment is that very few people actually pay attention to what stuff really costs.

Day 3 of Mastercheap Raw saw me heading to the office and a media launch: how will I cope with co-workers stuffing their faces? Plus: I've spent the last 50 cents.

Day 2 of the Mastercheap Raw challenge was Sunday: no need to go anywhere, and a host of vegetable-centric dishes to prepare. But first let's talk about breakfast.

The Mastercheap Raw experiment has begun! I've spent my $25 and it's time to start actually cooking and eating. How much advance preparation am I going to need, and how will I cope with going to a fully-catered event on the very first day?

So I have $25 to feed myself for the week and I have to make more or less everything from scratch. What made it onto the Mastercheap Raw shopping list?