"I changed my diet completely, so lots of vegetables," the 31-year-old former world number one said.
"I [altered] my mind frame completely because I was the person who always ate their steak first and their salad second."
The lifestyle change follows her shock withdrawal from September's US Open with Sjogren's Syndrome, a chronic disease where white blood cells attack moisture-producing glands and can cause dysfunction of organs and body systems.
The seven-times Grand Slam champion suffered with fatigue and swelling because of the illness and has slipped to 103rd in the rankings having not played much this year.
"My goal next year is to play a full schedule. It will take some work to get there, but I'm no stranger to hard work," she said.
"I love the game. The racket feels right in my hand and I'm planning on going right back to where I was at the top of the rankings in the singles and doubles sometime within the next 12 months."
Williams's last Grand Slam singles triumph was her 2008 Wimbledon crown.
Since then, younger sister Serena has won a further five Slams to take her tally to 13, although she has struggled for form after suffering health worries of her own, such as a pulmonary embolism earlier this year.
"Her achievements over the last years have been monumental and even with health issues she's been able to continue to be great, right now I think she's one of the best players in the world," Venus said of her sister, the world number 12.
Five-times Wimbledon champion Venus said she had no time for anything outside tennis and her business interests, which include a fashion label and an interior design company,
"It's so much fun being single - at some point I'll be mature, but it just hasn't happened yet," she said. "I'm shocked at myself by my inability to settle down and to commit to anything besides tennis and work."
She added she would never date a fellow tennis player.
"Those are my colleagues," she said. "Handshake, that's it."