On Monday I arrived in a small, strangely lit room at the University of Birmingham, my blotched face nipped by the winter wind and each arm laden with hessian bags, clanging with the sound of old pots and pans used in my latest leftovers cooking challenge. I clattered my way to the remaining seats on the second row with ten seconds to spare before the film started rolling.

This was Birmingham's premiere of Just Eat It: a 75-minute documentary about food waste and food rescue. It wasn't one of those questionable homemade conspiracy-theory films that you find on popular video-streaming sites. It was great to see that those campaigning for the cause don't pluck numbers out of thin air. The facts were nonetheless shocking. A third of the worl’s entire food supply never makes it onto a plate (UN; FAO). No matter how many times I repeat that one, it never becomes less shocking. I imagine taking the globe, cutting it into thirds and chucking one part away.

Filmmaker and subject Grant Baldwin finds a bin brimming with in-date hummus.

The Just Eat It documentary features interviews with key experts on food waste, like Dana Gunders, Jonathan Bloom and my personal hero: author, activist and founder of Feedback, Tristram Stuart. Yet the saddest part was hearing from those in the industry, all along the supply chain, from the truck drivers to the cashiers. Even among the harvesters who strip bunches of celery to half their size to form the celery 'heart' sold in supermarkets, leaving the rest to rot on the field, there was unanimous agreement that food fit for human consumption should never go to waste.

But they also shared a degree of despondency. Where will the change come from?

Should we, the consumers, subvert the system by collectively starving the supermarkets of demand for their products? Too many people are too busy for this to gain much traction. We can start by changing our household habits: looking in the cupboards before doing a shop, freezing food we know we won't be able to use on time. Portioning rice rather than guessing. But what else can we do?

Harvesting celery. An estimated 20% of produce never leaves the farm (WRAP)

One campaign established by Stuart's charity Feedback is the Gleaning Network. Gleaning is about collecting left-over crops and redistributing them to the vulnerable or needy. It's a great way for consumer's to recover food waste outside of the household. However, there have been questions about liability...

What happens if recipients fall ill from donated food?

In the US, retailers can rest in the assurance that a 'Good Samaritan Law' prevents legal action against donors and distributors of food. A similar law was rejected by the House of Lords in 2014, ruling that the introduction of such a law in the UK is a "solution looking for a problem". Surely at the least it would prevent the "we might be sued" excuse. And why do supermarkets prevent skip diving when 1) Legally, it isn't 'stealing' because once thrown away, the food is of no monetary value to the supermarket, 2) There has been no single court case over skip-dived food.

Then there's date labelling. In the US, the only product required by the federal government to have a date label on it is baby formula. Anything beyond this, particularly the use of multiple terms: 'best-before', 'display until', 'sell by' and 'use by', is bound to confuse.

But why would supermarkets scrap labels when they profit off people wasting edible food? The sooner households throw food, the sooner they need to purchase more. And in terms of their own waste, why bother trying to pass it on elsewhere when...

...it's cheaper for supermarkets to discard excess food rather than redistribute it.

So it seems to me that the onus lies on a higher power, i.e. the government, to impose regulations. Regulations are not there to be liked by all, after all. Then why do the EU set regulations about the exact curvature and diameter of bananas? Is it any wonder that some men experience insecurity when bananas are subject to even higher standards?!

Just Eat It also took us on a journey with the film's director, Grant Baldwin and his wife, Jenny Rustemeyer as they challenged themselves for six months to eat only food that would otherwise go to waste. In the six months, they brought home £14,000 worth of discarded food for the price of £140. The night before embarking on the venture, Jenny joked that she hoped there wouldn't be any 'dumpster diving'. At that point I knew she had set her standards too high; it's pretty difficult to intercept potential food waste before it's thrown in the bin. One grassroots organisation that has succeeded in doing so is The Real Junk Food Project.

Menu for TRJFP's Ladywood pop-up in Birmingham.

I promised to report back to you about my visit in December to TRJFP's Ladywood pop-up and failed to keep that promise. The team of volunteers operate 'Pay As You Feel' café using food that would otherwise go to waste. They've spent the last few years making the transition from supermarket bin to establishing agreements with food chains, restaurants and supermarkets. Absolutely passionate to eliminate food waste (in an ideal world, they would be out of business), their next step is finding funding that will enable explorations into alternative growing economies.

Gleaning networks run across the UK to distribute would-be waste to those in need.

Just Eat It and projects like The Real Junk Food Project, Fairshare, Foodcycle and Feedback make me want to do more. Gleaning. Campaigning. Finding out if my local ASDA has a food recovery programme. Jumping in bins!

Yet, while food recovery and freeganism would be great for my pocket, they don't change the fact that an exorbitant amount of food is produced, regardless of demand. The discussion after the film was a bitter reminder of how deep the problem is, and how the solution is far from straightforward when it comes down to economics.

I chatted afterwards with a student who "doesn't study, but reads economics". He believes that long term, we could reach a point of equal supply and demand, but only if supermarkets can get over the hurdle of making short term losses during the transition towards that point. If supermarkets started to sell all vegetables of all shapes and sizes, the sheer amount of supply would push down consumer prices. However, once farmers reduce their production to meet consumer demand, supermarkets would no longer suffer a loss in profits. So where do we go from here? Is there any way that supermarkets can eliminate the waste they are creating (indirect and direct) without hitting their profit margins in the short term?