What AI Body Scans Can (and Cannot) Tell You

We’re living through a full-fledged skinny epidemic. Even if seeing celebrities get thinner and thinner doesn’t mean anything to you, notice how marketing for various weight loss products is getting increasingly ubiquitous. When I look around, the onslaught doesn’t stop with all the ads for GLP-1s. What has really caught my eye recently is how I—a fitness writer who happens to be pretty thin—keep receiving targeted ads for different types of “AI body scans.” These services take a few different forms (which I dive into below), but what they all try to sell is the same idea: Apparently, I don’t know enough about my body. It turns out I need to know my body fat percentage, muscle mass, visceral fat, and of course, my "biological age."

Before I break down what exactly these AI body scans can (and cannot) tell you, know that this is not some takedown of AI tools being used by radiologists to spot cancer from a CT scan. What I’m focusing on here is all the false advertising for consumers like me, people naturally drawn to the shiniest tools to understand every little thing about their bodies. But before I build my health decisions around a number on a screen, I have to wonder about the gap between what these tools promise and what they actually deliver.

What are AI body scans, exactly?

Body composition scans are nothing new—it’s the AI angle that’s giving the market a fresh angle. The term "AI body scan" covers a range of technology, from clinical-grade DEXA machines used in research hospitals, to apps that claim to estimate your body fat from a selfie.

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At the serious end sits the DEXA scan (Dual-Energy X-ray Absorptiometry). Originally developed to measure bone density, DEXA uses two low-dose X-ray beams to distinguish between bone, fat, and lean tissue with genuine precision. It can identify visceral fat (the dangerous kind that accumulates around organs), regional fat distribution, and bone density. A single session might cost between $40 and $300 out-of-pocket, depending on where you go and whether any insurance applies. A company like BodySpec, for instance, has built businesses around making DEXA more accessible, performing around a thousand scans a day and building what it describes as the “largest proprietary DEXA dataset” in the world.

Below DEXA on the precision ladder sits “bioelectrical impedance analysis” (BIA). BIA is the technology powering most "smart scales," gym body composition stations, and many of those consumer-level AI scanners that keep targeting me with ads. BIA works by passing a small electrical current through your body and measuring how it travels. Fat resists electrical current; lean tissue (mostly water) conducts it well. From this resistance, the device estimates body composition.

Then, at the bottom of the technical hierarchy, sit the phone camera apps. Translating a 2D image into a body fat percentage or visceral fat estimate requires assumptions that are generous at best. These apps may be useful as very rough awareness tools, but so is a photograph.

Another note on "AI" in this context

Again, it's worth being specific about what AI is actually doing in most of these products, because as always, the word can mean a lot of things. In the better DEXA-based services, AI is being used to process and contextualize large datasets, helping users understand their results in comparison to relevant populations, flagging trends over time, and personalizing recommendations. For instance, BodySpec describes using AI to give its scanning service a kind of institutional memory for each client, stitching together health history and personal context so that consultations feel personalized at scale.

In consumer devices, "AI" most often means that an algorithm has been trained on a dataset to estimate body composition. But the AI is only as good as the underlying measurement, and those underlying measurements might not be accurate in the first place.

What an AI body scan cannot tell you

Let’s take a look at where the marketing diverges from the medicine, and where some skepticism is warranted. A body composition scan cannot tell you about your insulin sensitivity, inflammation, thyroid function, cortisol levels, or dozens of other physiological variables that determine your actual metabolic health. Two people can have identical DEXA results (same muscle mass, same body fat, same visceral fat reading), but one can have pre-diabetes while the other doesn't.

“I had two people with similar scan results, but very different metabolic health once labs were checked,” says Dr. Raymond Douglas, a board-certified oculoplastic surgeon and professor at Cedars-Sinai Hospital in Los Angeles. “And if you're making lifestyle choices based on a scan number alone, you may be fixing the wrong problem."

What’s more, that sort of interpretation of scan results ass