I was so shocked when I began receiving letters from my constituents about the implications for them of the bedroom tax, and about how little they would have left to live on, that I decided two weeks ago to see if I could survive on £18 a week, which is what they will be left with to buy their food after 1 April.

£18 is based on the experiences of my constituents, in particular women on employment and support allowance who have had to stop working owing to chronic health conditions, perhaps after 20 years of working life. Out of their £71.70, they have to find £10 for electricity, £20 for heating — gas or coal —£6 for water rates, £4 for bus fares and £10 for the bedroom tax, which left them with £23 for weekly living expenses.

That £23 has to cover more than food, of course. We did a calculation, and set aside £5 for all the non-food items everyone has to buy—soap, washing powder, washing-up liquid, toothpaste, loo paper—plus a small amount in order to save £50 a year for clothes or a pair of trainers, or in case the iron breaks. That leaves £18.

I therefore took up the challenge of trying to live on that amount. It was extremely unpleasant. I had porridge for breakfast every morning, as I usually do, but whereas I usually make porridge with milk, instead I had to make it with water. I had to eat the same food over and over and over again. Single people are hit particularly hard, because cheap food comes in big packs. I made a stew at the beginning of the week, and I ate the same food four nights a week. I had pasta twice a week. I had baked potatoes. I had eggs on six occasions. It was completely impossible to have fish as well as meat; that was out of the question. It was also impossible to have five portions of fruit and vegetables a day.

I therefore have a message for Anna Soubry, the Tory minister who recently criticised people on low incomes for obesity. Of course they have to fill up on toast and biscuits.

I found myself waking up in the middle of the night, absolutely ravenous, having to make cups of tea and eat biscuits. I had a headache for five days week, and I was completely lethargic and exhausted by 4pm. Some people are on Jobseeker’s Allowance and are looking for a job. Looking for a job is a job in itself; it takes time and energy. The people whom DWP ministers want to do workfare are being expected to work 30 hours a week, yet they are not going to have enough to eat properly.

Most shocking of all was the fact that come Sunday I ran out of food - there was literally nothing left to eat that night. If ministers are happy with the notion that 660,000 of our fellow citizens are literally not going to have enough to eat by the end of the week, they have no conception of what they are going to do to the people in our constituencies who will be faced with this bedroom tax.

Ministers have been very free and easy in talking about alternatives, such as the fact that people can move. In my constituency, more than 1,000 people will be affected by the bedroom tax but there are fewer than 100 smaller properties to which they could move. In my constituency, it is not possible for all these people to increase the number of hours they work, as seven people are chasing every job; people are in part-time work because they cannot get full-time work.

Of course some individuals or couples have properties that are larger than they need, but the so-called under-occupancy is in one part of the country and the overcrowding is in another. It is simply not credible to suggest that all the large, over-occupying families in London will move up to Durham, particularly given that the unemployment rate there is more than 9 per cent. What would they be moving to?

I made a video diary of my week, so I got a lot of feedback from people affected by this policy. Interestingly, they said, "Yes, this is the reality of our lives. We are not able to survive properly now and things are going to get worse to the tune of £10 a week from 1 April." In 2006, I did the same experiment under the previous Labour government, living on benefits to see what life was like for young people on the lowest rate of income support. I found that difficult, but there was enough money to get through the whole week. I wish to point out to the minister that we have reached a new low, because the £21 that people had in 2006 is equivalent to £28 now, and that should be compared with the £18 from 1 April.

Government ministers also constantly refer to how discretionary housing benefits can solve the problems created by the bedroom tax. In County Durham, £5m of income will be taken out of people’s pockets and out of the local economy. The size of the discretionary fund is half a million pounds, so once again there is a huge gap between actual need and the resources being given to people to deal with it.

The bedroom tax is a fundamental attack on the poorest people in this country. People are going to lose between £500 and £1,000 over the course of next year, through no fault of their own. But the really disgusting thing is that on the same day that the bedroom tax is being introduced, millionaires are being given a tax cut that will be worth £1,000—not over the year as a whole, but every single week.

Helen Goodman is Labour MP for Bishop Auckland and shadow media minister

You can watch her videos from her week living on £18 here