Speaking at Berkshire's annual shareholder meeting in Omaha, Nebraska, Buffett said it seemed "spurious" to argue that calories from Coke alone were a significant factor in obesity levels.
Hedge fund manager William Ackman, among others, has said he would not own Coke stock.
But Buffett, 85, noted that he consumes about 700 calories of Coke a day, saying "I'm about one-quarter Coca-Cola," and that he had seen no evidence that switching to "water and broccoli" would make it easier for him to make it to age 100.
"I elect to get my 2,600 or 2,700 calories a day from things that make me feel good when I eat them. That's my sole test," he said. "I like fudge a lot. Peanut brittle. I am a very, very, very happy guy."
Berkshire owns 400 million shares of Coke, about 9 percent of the company.