People often turn to sites like Yelp! to read reviews posted by others before making a purchase or choosing a restaurant. This same principle of crowdsourcing — asking for ideas, services or feedback from a large online group — also helps if you're dieting.

Crowdsourcing via a mobile app helped people make smarter food choices and lose weight, according to a study by American and Finnish researchers.

We know that self monitoring is the key to weight loss, but we need to find innovative ways to get people to do that.

Using the app, called Eatery, people rated the healthiness of food in smartphone photos. But the app users could also use photos to help each other avoid foods that could ruin their diets.

The investigators uploaded onto the Eatery app 450 photos of meals from 333 unique users in Europe and the U.S. Participants rated their meals on a ‘healthiness’ scale from ‘fit’ (healthy) to ‘fat’ (unhealthy), and could also similarly rate the "food" photos from other Eatery users.

Three public health students were asked to rate the same pictures, using a more complex scale based on the 2010 U.S. Dietary Guidelines. The students deducted points for unhealthy foods and added points for healthy ones.

The researchers found that participants were able to rate food choices just as effectively as the public health students who had taken classes in dietary assessment.

“It was surprising that untrained users of the Eatery app did such a good job assessing the healthiness of the food and beverages in the photos,” Gabrielle Turner-McGrievy, corresponding author on the study, told TheDoctor.

“Whether or not they actually ate better foods is another thing, but they were at least knowledgable about what they should be doing,” she added.

Researchers think crowdsourcing can help inspire healthier eating because people feel they are held accountable for what they eat to someone other than a doctor or family member who wants them to lose weight.

The app's other value is the social support and social comparison it offers, said Tuner-McGrievy, an assistant professor at the University of South Carolina Arnold School of Public Health.

“When you send out pictures for others to see, you probably want to send out photos of healthy things and you want to get good ratings, and that may impact your food choices,” she explained. “We know that self monitoring is the key to weight loss, but we need to find innovative ways to get people to do that.”

If taking smartphone pictures of your meals and sharing them with friends helps, do some crowdsourcing and have them give you feedback on your meals. You could also give feedback to friends on their meals, essentially creating a buddy system.

Though the Eatery app is not presently available, Turner-McGrievy's team hopes to make the app as fun as possible, possibly by including games, “People play Angry Birds on their phones and tablets, so it would be good to add some entertainment value to this method of taking pictures to incentivize people to use it.”

The study is published online in the Journal of the American Medical Informatics Association.