There's no getting away from the fact we are all consumers - even if we had the strength of character to jettison the less essential purchases, we still have to eat. Alastair Plumb takes a look at the ways in which we can all approach the weekly shop with a greener attitude, without piling on the expense or promising to live on lentils for ever more.

We all know we should be doing a little be more for the environment.

But when it's 10pm and you've run out of milk, sometimes all you can do is jump in the car and scream down to the nearest supermarket.

But our supermarket shopping choices affect more than just the content of our dinner plates - every decision from how to get there to what to put in the shopping basket has a knock-on effect for the environment.

So what can we do to help things?

Everyone needs to do their weekly shop but there are ways of making sure we do things a little greener.

Getting there
Research carried out by Somerfield shows that although 67 per cent of us have a grocer within walking distance of our homes, the average shopping journey by car is 2.4 miles long.

Driving to the shops may be convenient but the carbon dioxide emitted on regular short journeys makes it bad news for the environment.

Seventy-four per cent of Londoners walk to the shops but elsewhere the statistics aren't so promising.

Find out where your nearest convenience store or grocer is and try walking there. Not only is it good exercise but local retailers also tend to sell more local produce, which is fresher and often cheaper than buying products sealed in plastic and flown halfway across the world.

Many supermarkets have now set up cycling racks by their stores to encourage greener modes of transport, and more and more local shops - especially in city centres - have limited parking spaces available, making driving less of a convenience and more of a chore.

Shopping list
Making what your food is transported in uses huge amounts of energy, especially if it's plastic.

Think twice before buying pre-cut food: items such as sliced carrots in a bag require more energy and more manpower than buying loose carrots and preparing them yourself.

James Colwill from Packaging Europe is keen to point out the problem: "Consumers tend towards convenience but in so doing can work against themselves."

As a general rule, the more complicated the packaging, the more wasteful it is and the more it's trying to make up for something. Try to avoid any overtly attention-grabbing packaging, such as toothbrushes in boxes three times their size.

But it seems we may already be turning away from unnecessary wrapping. At one point, Sainsbury's offered a pre-peeled orange as part of their fruit range. Sales were strong for the first few weeks but after the initial high, customers backed off.

In making a sealed item without the natural protection, more additives and chemicals are needed to keep the food from going off.

At the checkout
The major battle ground for supermarkets of late has been the world of plastic bags.

In the pursuit of a more environmentally- conscious shopping experience, these white polyethylene sacks are key, and the statistics are astonishing: six billion bags are wasted every year by shoppers - enough to cover the whole of London.

Tesco, for example, has recently been charging home its new "Green"

campaign, offering Clubcard points for customers who buy fairtrade products and recycle ink cartridges, mobile phones and, notably, plastic bags.

Somerfield, like the Co-op, has been using biodegradable bags for more than five years now.

The Republic of Ireland has charged 10p per bag since 2002 and firms in the UK have followed suit, with Ikea, Aldi and Lidl all charging customers for bags to encourage environmental responsibility.

Waste plastic bags account for 20 per cent of the nation's landfill volume, so buy a "Bag for Life" and keep reusing it - shops will offer free replacements if they wear out.

Better yet, buy a solid shopping bag (more and more are available, with many designers creating their own) and bring that along instead.

What more can we do?
Believe it or not, you can change the way supermarkets work.

Supermarkets keep a very close eye on what's being bought and what's not.

Loyalty cards allow them to see just what you're buying - so vote with your card. If you buy more fairtrade and environmentally-friendly products for example, they will take notice.

Here are a few more ways to make a difference: If you are going to drive to the supermarket, do it with a friend. You can save petrol and time as well as making a normally tiresome experience a bit more fun.

Make sure when you drive to the supermarket the boot is full of everything recyclable you've used that week. There are recycling deposit points in most of the larger stores so use individual bins for glass and plastic, as well as getting rid of old magazines and newspapers.

Check where your food comes from - products should have country of origin details, and some shops, such as Marks & Spencer now carry airmiles information.

If your local supermarket is selling produce that could easily be grown nearby, try and make sure you buy local to discourage them from buying abroad and causing transport pollution.

How do the supermarkets compare?
The National Consumer Council (NCC) recently carried out research into the green credentials of the major supermarket chains.

Results (see box) were disappointing for Somerfield and Morrisons, which scored the lowest in the tables, taking into account environmental standards on transport, waste and sustainable farming.

The chairman of the NCC Lord Whitty has said, "We all need to understand that food is the typical household's number one contributor to climate change... By throwing away ten billion carrier bags each year and transporting carrots from Egypt and strawberries from New Zealand, we hit the environment hard."

But remember, it's our choice and we can all make changes if we want to.