Kennedy, who had only been in the role since October and resigned from government in protest at Gordon Brown's style of leadership, had won many friends with her straight talking and common sense approach to the obesity debate.
"I'm extremely disappointed that she had to go so soon," said PTF director general Clare Cheney. "She was a breath of fresh air, in touch with the real world, not afraid to stick up for fair play and common sense regardless of the bureaucracy that pushed in the opposite direction. We need more ministers like her."
Earlier this year, Kennedy endeared herself to the farming community at the NFU conference when she argued that while obesity was a major problem in Britain that there was a danger "we as a nation are almost schizophrenic about food."
She also slammed the FSA's satfat awareness campaign, arguing that shoppers should be allowed to choose good quality full-fat cheese and milk if they preferred the taste.
"I am sometimes really disappointed with some of the agencies we rely upon to give us advice on these matters," she said of the FSA at the time.
Kennedy's stance was praised by Dairy UK director general Jim Begg, who described her as a sympathetic and able minister capable of balancing the needs of farmers, food manufacturers and consumers. "She endeared herself to farmers and the dairy sector by questioning the FSA's obsession with single nutrients and advocating a common sense approach to balanced diets," he said.
"She was a strong supporter of the dairy industry and did Dairy UK the honour of attending events. We hope her successor takes a similar stance."
Fitzpatrick, MP for Poplar and Canning Town in East London, has little experience with the food or farming sector. He is understood to be a member of Greenpeace and a keen supporter of animal rights.