Fast food, the sustainable way

It is thanks to a childhood passion for the Whopper that I came to be interested in the sustainability of food. Like John Vincent, my business partner, I grew up associating fast food with the end of the holidays - a final fling before returning to school. John's dad, Leon, after whom our restaurants are named, tells me that John used to get so excited about his trips to McDonald's that he would lie on his front beforehand and thump the floor with his fists. My vice was Burger King - the butterflies would riot in my stomach as we walked down to Putney High Street for the pre-cinema supper.

Then, we grew up. And our waistlines grew with us. We realised that fast food has hidden costs, mostly in the gut department. The idea behind Leon was not altruistic. It was selfish. We couldn't find any fast food that wouldn't make us fat, so we decided to make it ourselves. And it became clear that, even if we hadn't given much thought to the welfare of the planet, it was important to those who ate with us. We wanted to live up to their expectations. One of the first things we decided as a matter of policy was that our fish would come from sustainable shoals. We took advice and decided to limit our buying to mackerel and coley. We quickly realised that this was too simplistic. Coley is caught sustainably in the north-east Arctic, the North Sea, Skaggerak, west of Scotland and Rockall, but is at risk of being harvested unsustainably in Iceland or the Faroes.

Even defining species by area is not good enough. Nature does not stand still. The Barents Sea has been warming since the early 1990s, leading to the recent bumper cod stocks. Over the past few years, this warming appears to have been luring migrating mackerel further north, away from Scotland and towards Iceland, which is allowing its fishermen huge mackerel quotas. The Scottish claim that this is putting mackerel stocks at risk. Try asking any restaurant that is dealing with food inflation and a consumer recession to get their heads round that.

The actions of a few restaurants in the UK are not going to be the solution to the planet's quest to feed itself sustainably, but the sector has political clout. A significant proportion of what consumers in the UK spend still goes on food. Restaurants have some ability to demand changes to the way we produce it.

At Leon, we've spent the past seven years trying to work out how to source responsibly, reduce our energy use and cut back on packaging. I've spent more time than I care to remember in a hairnet and a sanitised boiler suit, watching fish fingers come off the production line or wading through seas of poultry. I have learned how to spot line-caught fish (the flesh is whiter because, unlike net-caught fish, they are bled live) and recognise the ammonia burns on chickens' legs caused by overcrowding. (Those bright purple marks you sometimes see at the supermarket? Avoid.)

What became apparent was that the issues were too complicated for any restaurant to understand on its own, which is why we helped to set up the Sustainable Restaurant Association, a not-for-profit body that aims to guide restaurants. We know enough now to understand just how far there is to go. But, with luck, these baby steps will be among the millions taken, so that our children will be able to feed their children sustainably.

Henry Dimbleby is co-founder of the restaurant Leon