For the last week I have been fasting in solidarity with the men on hunger strike in the US prison at Guantánamo Bay, forgoing all food and taking only liquids. I began day one thinking about a book I had recently read: former detainee Ahmed Errachidi's The General. Errachidi had worked as a chef in London for 18 years but was sold for a bounty to US forces after he travelled to Pakistan. He was finally released from the prison in 2007, but not before he had been held in isolation for three years and tortured relentlessly. The book describes his five and a half years in Guantánamo, being abused along with his fellow detainees.

Reading about his being delivered into the hands of sadists who inflicted punishment day after day and told him his case would never come to trial, you can begin to understand why the hunger strikers in Guantánamo feel they have no other recourse. I thought about what it would take to endure a real, long-term hunger strike with all the pain – physical and emotional – involved. How hard it must be when you have no idea how long your strike must last – an indefinite fast – just to secure some basic justice.

I embarked on this project because I hope it will make some small contribution to Reprieve's StandFast campaign to raise awareness of the Guantánamo hunger strikers, and make people realise the basic facts of what is going on there. More than half of those held have been cleared for release by the US government yet remain in prison due to a lack of will by that same government.

It is unfathomable that the US authorities refuse to release prisoners who have been cleared of any charges and who have countries that will admit them at once. Take Shaker Aamer, one of the prisoners on hunger strike. He is a British resident who has a British wife and four British children, the youngest of whom he has never met.

Aamer's family have waited day after day, year after year, hoping that he will one day return to them. The British government has said that it wants him back in Britain, and David Cameron has raised his case with President Obama – yet Aamer still languishes in Guantánamo.

Luckily for us he writes regularly from there, and recently gave his advice to hunger strikers. He has protested his indefinite detention in this way so often that he is now something of an expert.

It was by the fifth day that I realised how many scenes of people eating there were on television. I was obsessed by the longing for taste. This is what we often hear from Reprieve's hunger-striking clients. Younous Chekkouri has told his lawyers about the vivid dreams he has had since he began his hunger strike, of mountains of his favourite foods, not tasted since incarceration began.

I have the luxury of knowing that I will finish my fast soon, and of not being shackled to a chair so that tubes can be shoved into my nose and throat and a nutritional supplement pumped into my stomach to feed me against my will. The men in Guantánamo have to go on and on and on until Obama starts doing what he could have done months, indeed years ago – sent the cleared men home. Until that happens, they continue to hunger strike. Their strength of will is staggering.

On day six I learned from an article in the Nation that the threat of Aamer being forcibly sent to Saudi Arabia has increased. It is deeply shocking. And the campaign becomes more important than ever.

And so, on day seven, my fast is drawing to a close. The difficulty in not eating has been more mental than physical – the endless array of food dishes that dance in your mind so persistently. Now it's almost time to eat I feel I shouldn't: the job is not done, justice is not done. They are still inside. I feel a sense of betrayal that we carry on with our normal lives while these men are still suffering. I can only hope that Reprieve's efforts serve to disrupt the normalisation of the inhuman treatment the hunger strikers are undergoing. Best wishes to whoever among you might decide to pick up the baton.