Jean-Claude Juncker denied he has a problem with alcohol during an interview in which he drank four glasses of champagne.
Allegations have circulated in Brussels in recent years about the head of the European Commission's drinking, with one senior diplomatic source even saying he "has cognac for breakfast".
Over a lunch interview with a French newspaper, Mr Juncker defended his record as he consumed several glasses of champagne.
In 2014, it emerged that his drinking habits had been discussed at the highest levels by European leaders who privately harbour concerns about his lifestyle.
A week before Britain's EU referendum, a video emerged of an apparently drunk Mr Juncker at an EU summit in 2015 - he welcomed Viktor Orban, the hardline Hungarian prime minister, as "the dictator" before giving him a playful slap on the cheek.
He then locked Mr Orban in an embrace while Donald Tusk, president of the European Council, watched, visibly embarrassed.
Defending himself in an interview with Liberation, he said: "Orban, I always call dictator, I am like this.
"As soon as someone breaks the mould they are obviously crazy or an alcoholic. You think I'd still be in office if I was having cognac for breakfast?
"It really makes me sad and it has even led my wife to question if I lie to her, as I do not drink when I'm home."
Mr Juncker blamed his unsteady walking on a serious car accident in 1989, after which he spent three weeks in a coma and six months in a wheelchair.
"I have a balance problem with my left leg that requires me to grab the rail when on a staircase," he said.
"After a lunch I grabbed a Dutch minister by the arm and he said that I was drunk."
Mr Juncker insisted that the only "personal problem" he suffered from is fatigue.
"Being president of the European Commission is not the same as being prime minister of Luxembourg," he said.
"I have to work 14, 15 hours a day and that I was not used to."