Techies are dieting by loading up on meat and veggies for a full month

Key Points
  • The Whole30 diet includes fresh meat and vegetables and excludes sugar, dairy and wheat.
  • "I noticed a huge life improvement," said one entrepreneur.
Whole30 diet: What you can and can't eat

There's always a new restrictive diet making its way across Silicon Valley.

One of the more popular fads these days is the Whole30 diet, which involves cutting out grains, beans, alcohol, sugar, peanuts and dairy for 30 days. On the menu: fresh meat, fish, veggies and eggs.

The diet originally took off on Instagram, where the #Whole30 hashtag has now accumulated more than 3 million posts. That's where Olivia June, founder of the Vina social networking app, initially discovered the nutritional regimen. Three years ago she was on a quest to feel better, both emotionally and physically, and she's been incrementally doing the diet ever since.

"I noticed a huge life improvement," June told CNBC.

Others like venture capitalist Matthew Kinsella were less impressed. Kinsella tried out the diet for a month last year and recalled feeling constantly hungry.

The Whole30 is designed to alleviate that tired and lazy feeling in the afternoon when many of us will reach for a cup of coffee. But Kinsella said, "I didn't feel any energy at all."

The website for the Whole30 warns users about a number of potential unpleasant side effects. For example, on days two and three you may experience "headaches, fatigue, and general malaise," and then on days six and seven, it may feel like "it's 10 am and all you can think about is crawling under your desk for a catnap."

Oliva June has been doing the Whole 30 diet on and off for three years.
Magdalena Petrova I CNBC

June said the struggle was worth it and the Whole30 diet felt like a cleanse.

She said she decided to do it after feeling that her system was "out of whack" and to get a break from processed foods.

Ethan Weiss, a cardiologist at the University of California, San Francisco, said there isn't much evidence to support the view that the Whole30 is beneficial to human health, at least in the long run.

"It would be hard to imagine that a 30-day diet once a year would have a meaningful impact on any health perimeter that I could measure or care about," he said. "But it's not impossible."