Food tracking is one area where digital health still hasn't meaningfully surpassed the status quo. Sure, it's easier to log your food in an app than it is with pen or paper, but unlike step counts, heart rate, blood pressure, and more, there's no connected device that automatically knows what you've eaten and how many calories you've consumed. It's something of a holy grail for consumer tracking devices, and maybe that explains why it's an area that's been populated by some sketchy startups over the last year and a half.

Three once-promising startups, Airo, HealBe and TellSpec, are on a spectrum between "not ready for prime time" and "outright scam." A third, SCiO from a company called Consumer Physics, still looks like it could be the real deal. Read on for a roundup of would-be calorie tracker drama.

The first company to promise passive calorie tracking -- and to subsequently disappoint its customers -- was Ontario-based Airo back at the end of November 2013. Just three weeks after a successful crowdfunding campaign, it told early backers via email that it had refunded their money and would not put the device back up for sale until it has been tested and validated further. There hasn't been any word from them since.

The next device, the HealBe GoBe also raised a ton of crowdfunding money in 2014, but launched early this year. That company was subjected to much scrutiny by PandoDaily, who pointed out, among other things, a lack of evidence that the device actually tracks calories or nutrition as advertised. In January of this year, it finally launched (or at least sent out test devices to a number of journalists) to mixed reviews. Even those that proclaimed the calorie tracking function accurate found the device buggy, and others considered the calorie tracking features a total bust (in addition to finding the device buggy).

TellSpec, a miniature spectrometer that claimed to be able to deliver information about allergens, chemicals, nutrients, calories, and ingredients in food that it scanned to a user's smartphone, also raised a lot of crowdfunding money and has so far failed to deliver a product or refund its backers. That saga continued with TellSpec launching another crowdfunding campaign on an investor-focused website, which it was forced to take down after Pando highlighted fraudulent claims in their slide deck.

One more product out there with a successful crowdfunding campaign and a promise of passive food tracking is Consumer Physics, which makes a device called SCiO. SCiO's claims are more modest, specifically telling consumers not to use it for food allergies and admitting that it may not start out perfectly accurate, though accuracy will grow with a user-generated database. The device also has a $4 million investment from Khosla Ventures.