Unshaven and wearing only loose black trousers, Mr Chalad's shrunken frame looked a poor match for the power and wealth of the institution he is confronting: the military, the bane of Thai politics and stagers of many coups since the king gave up absolute power in the 1930s. But few have forgotten that it was a similar hunger-strike by Mr Chalad two years ago that started demonstrations in Bangkok against the unelected prime minister, General Suchinda Kraprayoon. They were bloodily suppressed on General Suchinda's orders, leaving at least 52 people dead and many missing.
Public outrage and intervention by the Thai king forced General Suchinda to step down after the massacre. But two years on, the generals have quietly regained much of their influence in the political world, not least because the constitution, which they wrote in 1991 after their last coup, guarantees a strong voice for the military in the country's affairs. For example, more than half the senators, who are appointed by the prime minister and not elected, are serving or retired military officers.
Mr Chalad is demanding that the constitution be rewritten to make Thailand a truly democratic society in which the military no longer has an effective veto over politicians. He says the government of Chuan Leekpai, installed after the demise of General Suchinda, has reneged on its promises to make Thailand more democratic. 'Chasing out the dictators but retaining their constitution is tantamount to inheriting dictatorial power,' he said as he began his hunger-strike.
Mr Chuan, criticised for being weak and indecisive, did try to make some changes to the constitution but was frustrated in March by an alliance of opposition parties in the lower house and the military-dominated senate.
The military has been extremely successful in making money from logging, arms sales, property transactions and private businesses, and will go to considerable lengths to protect its position. After being rebuffed in March, Mr Chuan has shown little appetite for taking on the military again, just as he has shown little determination to confront Thailand's other great problem: Bangkok's traffic congestion. He has tried to shrug off the hunger-strike as a political stunt with little public support.
The police threatened to arrest Mr Chalad on charges of attempted suicide, until a Thai-style compromise was agreed. While he continues to refuse food, Mr Chalad allowed a doctor to put him on a saline drip to stop dehydration. His body continues to weaken, but at a slower rate.
The hunger-strike has yet to attract the big crowds of the demonstration two years ago. But the group of supporters sitting outside the parliament with Mr Chalad has swollen steadily day by day; more than 1,000 people crowd outside parliament's main gate. They wore headbands and T-shirts criticising the 'dictators' constitution' and stalls were selling posters showing the killings of two years ago.
'It is the wicked circle of Thailand,' said Charoen Meechai, a teacher who joined the protesters. 'We have a government for a while, then a coup d'etat, a new constitution, an election and a government. Then another coup, another constitution and so on. For over 200 years America has had just one constitution, because it was written for the people. In Thailand, in the past 62 years, we have had 15 constitutions.'
The protest is not without its theatre: next to the supporters of Mr Chalad is a group of right- wingers who are against the campaign to reform the constitution. They have been cooking food on the street and staging 'eat to death' protests to mock Mr Chalad. As a sign of solidarity with Mr Chalad, some of his supporters have had their heads shaved, including one British tourist who had come down to the parliament for a look: 'I read about it in the local papers,' said Ian Blake, who left Bristol eight months ago with a full head of hair.
The Thais are a gentle and predominantly Buddhist people and for many ordinary citizens the idea of taking one's own life for any abstract ideal is disconcerting. But like it or not, the hunger-strike has reminded many that two years after the military's apparent exit from politics, their role in Thailand is far from settled.