Suggestions that Obama's slim physique is a liability in a nation of mostly overweight voters has now marked a dangerous new turn for the Democratic contender's suddenly vulnerable presidential campaign. Obama's craze for exercise first raised eyebrows last month, when he stopped three times in one day for workouts at Chicago gyms, prompting a reporter to wonder: "Sometimes it's hard to tell if Barack Obama is running for president or Mr Universe."
It has also been widely noted that Obama sometimes seems appalled when presented at election meetings with the pride of local cuisine, often a fat-smothered hunk of meat or a sugary bun dripping in aerosol cream.
While most candidates tend to tuck in fearlessly, thereby assuring themselves positive coverage in the local paper, Obama once visited a chocolate factory in Pennsylvania but turned down a piece of cake on the grounds that it was "too decadent for me".
Government statistics indicate that two-thirds of the overall voting population is overweight and almost a third is obese.
Yet, the 6ft 1in senator is reckoned to weigh 10lb-20lb less than the 190lb recommended weight for his height.
The notion that Obama is too thin to win was derided by many of his supporters, but the issue underlined a disturbing reality for the Democratic candidate.