Gluten-free dieting appears well on the way to becoming a sustainable trend while other popular diets seem to be losing ground, says Rochelle Bailis, director of content and insights, Hitwise, Los Angeles. After surging early in 2016, interest in low-carb and paleo dieting may be fading.

Analyzing food industry trends based on internet search numbers, Ms. Bailis says a key to distinguishing legitimate food trends from fads is sustained growth year after year.

“The holy grail of legitimate food trends is the ‘steady riser,’ a movement that has grown gradually in awareness and market share over many years,” she says.

For example, interest in organic food dates back to the 1940s, Ms. Bailis says. Despite this track record, organics remain strong into the 21st century. Hitwise analysis found a 224% jump in searches for organic food terms between 2014 and 2016, she says.

Hitwise bases its analysis on data gathered from a panel of 8.5 million people, tracking their on-line behavior across 20 million web sites and 500 million search terms. Hitwise is part of Connexity, an e-commerce and consumer analytics company.

Gluten-free dieting demonstrates “all the hallmarks of a ‘steady riser’ diet,” Ms. Bailis says.

While experiencing a scattering of “blips” she says searches for “gluten-free” climbed steadily during the analysis period, rising 141% between 2014 and 2016.

More cyclical has been interest in the term “detox.” Ms. Bailis attributes a July 2014 spike in searches to sudden interest in the wake of research studies about the detoxification properties of niacin published in the New England Journal of Medicine.

Ms. Bailis characterizes several diets as “so last year,” mostly based on ebbing interest in late 2016.

Low sugar diet searches showed growth during the 2014-16 period, but the gains were concentrated during a period in early 2016.

“Since then interest has essentially flat-lined,” she says.

Even more dramatic was growth in interest in “low-carb” dieting in early 2016, Ms. Bailis says. That surge was followed by a slow, steady decline over the balance of the year.

“That being said, since 2014 low-carb searches have still increased by a sizeable 223%,” she says.

Similar to the arc of “low-carb” dieting has been the pattern for “paleo” searches. After a “meteoric” jump in 2016, interest has dissipated, Ms. Bailis says.

“That doesn’t necessarily mean that the paleo diet trend is dead but serves as a reminder that fast-rising food fads carry the risk of falling out of favor quickly,” she says.

Ms. Bailis’ analysis includes two “rising stars,” diet searches that show a sudden upswing of promise.

“Vegan” searches have been steadily climbing since 2014, and at the end of October jumped suddenly into the league of ‘rising stars’ by doubling in volume,” Ms. Bailis says. “This abrupt interest in veganism is quite startling, considering veganism has existed for decades.”

Searches for “vegetarian” experienced similar growth and “entrance into the league of rising stars” late in 2016, Ms. Bailis says. Growth has been steady for some time but more than doubled in recent months, she says.

“This sudden renewed interest in vegetarianism and veganism, along with the persistent demand for organic foods, suggests consumers are more invested in sustainable food movements that improve their own health while protecting the planet and other organisms.

The interest in different diets has been accompanied by skepticism, Ms. Bailis says. As a result, she said new product development aimed at tapping into trends should proceed with caution.

“Also our national desire to eat better continues to expand, it is imperative that food brands and consumer packaged food companies are able to distinguish between authentic food trends and ‘her today, gone tomorrow’ diet fads,” she says.