In an interview on CNN, Booker said eating an adequate diet was also harder than he thought it would be. Booker ends a week of eating only what he could afford if he was on the Supplemental Nutrition Assistance Program this weekend.
"It's a little more difficult than I imagined," said Booker, a Democrat. "I thought it would be good on eating on a tight budget, so I started out not really marshalling my food well, so I'm really cutting back now."
He said he had to abandon his coffee habit, resulting in headaches.
"Going out and getting a cup of coffee at Starbucks will wipe out your entire allowance for a day, and for a guy who was admittedly caffeine-addicted, I am now going through a bit of a withdrawal," he told interviewer Piers Morgan.
Booker, a Rhodes scholar and Yale-educated lawyer who grew up in the suburbs, has served as mayor of New Jersey's largest city since 2006. He would not speculate in detail about his political future, including whether he would run next year against Republican New Jersey Gov. Chris Christie.
He had kind words for Christie's response to Superstorm Sandy.
"Governor Christie and President Obama showed the right spirit during one of the worst natural disasters to hit in my lifetime in my state," he said.
Booker is sometimes compared to Obama. But he said he has no plans to seek the presidency and responded to a question with a question: "President of the New Jersey Star Trek Association?"