British Health Minister Anna Soubry said that the availability of cheap junk food means that poor people have grown fat over the last few years.
The minister said when she was at school, pupils from deprived backgrounds tended to be "skinny runts". But cheap and easily available junk food meant the situation has reversed, The Sun reported.
Soubry's comments, in an interview with the Daily Telegraph, came after she threatened food manufacturers with legislation unless they cut the amount of fat, sugar and salt in products.
The culture of "TV dinners" has eroded traditional structures of family life and led some homes to dispense with a dining table entirely, the minister said, adding it was heartbreaking that the poorest in the country were among the most at risk of obesity.
"A third of our children leave primary school overweight or obese," she said.
"When I was at school, you could tell the demography of children by how thin they were. You could see by looking at their eyes."
They would be described as "the skinny runts" because they were not getting the right food, she added.
"When I go to my constituency, in fact when I walk around, you can almost now tell somebody's background by their weight," Soubry said. "Obviously, not everybody who is overweight comes from deprived backgrounds but that's where the propensity lies."
The Child Poverty Action Group, a British charity working to alleviate poverty and social exclusion, however said cuts in government support for the low paid and unemployed would make obesity worse.