Should You Get A Preventive Full-Body MRI?

Fitness
Written By John Solokas

“Grocery Store Joe” from The Bachelor got a preventative full-body MRI from Prenuvo. It found a brain tumor. They caught it early, removed it, and his prognosis is good.

“Holy smokes. Good for that guy. Should I get one too? Better safe than sorry, right?”

That was my reaction, at least. But then I looked at the evidence, and it turns out the answer is much less satisfying.

3 Things We Know:

Let’s start with three facts.

1. Whole-body MRIs do find cancer.

In studies of healthy, asymptomatic people, whole-body MRI detects confirmed cancer in roughly 1 to 1.6% of those screened.

That's not nothing. Joe's story is a compelling example of what the technology can do.

2. But it finds abnormalities far more often than it finds cancer.

Depending on how “abnormal” is defined, roughly 78–97% of people have something show up on their scan. One review found abnormalities in about 95% of people, with roughly 30% having a finding that required additional investigation.

So we're looking at a test where finding something is incredibly common, while finding cancer is relatively rare.

3. Most importantly, we don't yet know whether screening healthy people makes them live longer.

That's the key question!

Not: “How many tumors did the MRI find?” But: “How many people who got the MRI ultimately lived longer or avoided serious illness because they got it?”

We don't have a good answer yet. And that distinction - finding cancer versus saving lives - is the crux of the issue.

Why “we found it early” isn't enough

Suppose you screen 1,000 healthy people:

  • Maybe 940 have some kind of abnormal finding.

  • Maybe 300 need additional testing.

  • Maybe 10–16 are ultimately diagnosed with cancer.

That sounds pretty compelling until you ask a harder question: How many of those people are actually better off because they were screened?

There are three big reasons that number can be much smaller than you’d think:

1. Overdiagnosis

Some cancers grow so slowly that they would never have caused a problem during the person's lifetime.

Finding one doesn't necessarily help you. It can instead lead to biopsies, repeat scans, surgery, radiation, medication, years of surveillance, anxiety, or all of the above.

The cancer is there, the treatment can be thorough, and the benefit can still be zero.

2. Length-time bias

Screening is particularly good at finding slow-growing tumors because they hang around for a long time.

Aggressive tumors may grow and spread much faster, giving you a much smaller window in which to catch them.

So a screening program can look fantastic at finding cancer while disproportionately finding the cancers that are least likely to kill you.

3. Lead-time bias

Finding cancer earlier also doesn't automatically mean someone lives longer.

  • Imagine a cancer that will eventually kill you at 60.

  • Without screening, you develop symptoms at 58 and are diagnosed then.

  • With screening, an MRI finds it at 52.

You have now been diagnosed six years earlier, but you still die at 60.

Your time from diagnosis to death increased, but your life expectancy didn't. That's called lead-time bias. And it's why “we found it early” is not, by itself, proof that screening works.

The Problem With the Scan

Oncologist Vinay Prasad has a useful way of thinking about this.

Imagine three cancers that look identical on a scan:

  • One is so slow-growing it would never hurt you.

  • One has already spread and finding it earlier won't change the outcome.

  • One is deadly but curable if caught at exactly the right time.

You want the third one. The problem is that the MRI can't reliably tell you which one you've found.

So the first can lead to unnecessary treatment. The second can give you years of living with a cancer diagnosis without actually extending your life. And the third is the one you're hoping for, but may be the hardest to catch.

That's the gamble with whole-body MRI.

You're scanning everyone in the hope of finding the small subset of cancers where early detection dramatically changes the outcome, knowing you'll also find plenty of things that don't help the patient at all.

But calling everyone who buys one a sucker is missing something

Given the above, why are smart, healthy people willing to pay thousands of dollars for these scans? Because they're trying to solve a meaningful problem,

Modern medicine is very good at answering: “What's wrong with you, and how do we treat it?” It's much less good at answering: “I'm healthy. How do I become healthier?”

Or:

“How do I maximize my odds of staying healthy for the next 50 years?”

A healthy, fit person might ask:

  • How can I optimize my cardiovascular health?

  • What's the best way to preserve muscle as I age?

  • How can I reduce my cancer risk?

  • What should I be measuring, and how often?

  • How do I know I'm doing enough?

And medicine often has frustratingly unsatisfying answers.

The standard advice (exercise, sleep, eat reasonably well, don't smoke, maintain a healthy weight, get recommended vaccines and screenings) is right. But once you've done all that, there isn't a universally accepted “advanced prevention” protocol waiting for you.

That's part of why products like full-body MRI are so appealing.

And then there's Joe

Joe's story is incredibly persuasive. To be real, it makes me want to get a scan too.

Even if the chance of finding something dangerous is tiny, there's a powerful argument for paying a few thousand dollars to potentially catch a life-threatening disease before it causes symptoms.

But there's something you can't see in Joe's story: Everyone who got scanned next to him. The person whose MRI was normal doesn't go on Instagram and post: “Paid $2,500. They found nothing. Cool.” Neither does the person who spent months getting a suspicious kidney lesion, thyroid nodule, liver spot, or other abnormality investigated before discovering it was harmless.

That's the invisible denominator.

Joe's story tells us that a full-body MRI can detect a potentially dangerous cancer before symptoms appear. It doesn't tell us how often screening truly improves someone's outcome.

So is preventive MRI a scam?

I don't think that's the right question.

Is it a scam to sell a test that can find abnormalities and occasionally life-threatening cancers?

No.

Is there currently strong evidence that asymptomatic, average-risk people should routinely get whole-body MRI because it will help them live longer?

Also no.

Both things can be true.

The technology may eventually become much more valuable. Better imaging, better AI interpretation, better understanding of which findings we should pay attention to, and longer-term outcome data could change the equation.

I'd happily pay a few thousand dollars every couple of years for a scan if we eventually have good evidence that doing so meaningfully improves health outcomes.

We're just not there yet.

A full-body MRI might eventually become an excellent tool for preventive medicine. I hope in 20 years I’ll look back at this article like someone who wrote about prostate exams in the 1980s, before they were widespread (You want to put what where, and why??).

But now prostate exams are standard practice and save millions of lives every year. It’d be awesome if these scans end up being like that. 

What I'll do instead

I won't be getting a preventive whole-body MRI anytime soon.

At 30 and with my personal risk profile, the evidence doesn't currently convince me that the benefits outweigh the potential cascade of incidental findings and follow-up. So I'm putting my prevention dollars and attention into the boring stuff that has much better evidence behind it.

My personal* longevity checklist:

  • Keep body fat in a healthy range. For men, cardiometabolic risk starts climbing once you push past roughly 25% body fat, so I stay under 18% and keep my waist below 36 inches.

  • Train for the long game: at least 2 hours of cardio a week plus 3 strength sessions.

  • Optimize my bloodwork. For me, that means A1c under 5.7, triglycerides under 100, LDL under 70, and ApoB under 70.

  • Keep blood pressure good: <120/80.

  • Eat well: enough calories for my goal, plenty of fiber (I aim for 40+ grams/day), lots of fruits and vegetables, enough protein, red meat in moderation, and as little added sugar, saturated fat, and trans fat as I can manage.

  • Don't smoke and keep alcohol to a minimum.

  • Sleep well and consistently.

  • Get 8–10k steps a day.

  • Get the screenings that have actually been shown to work, at the ages and risk levels where they're recommended.

*Personal means applicable to me and only to me. These are based on my age, gender, training history, genetics, and risk tolerance. Some are personal goals rather than universal medical recommendations.

Nobody wants to die

That's ultimately why these scans are so appealing.

Nobody wants to be the person who could have caught something early but didn't. But constantly looking for the disease that might kill you isn't necessarily the same thing as preventing it.

For now, I think the rational approach is:

1. Take care of the big rocks.

2. Be proactive and advocate for yourself in a medical system that isn't designed around optimization.

3. Don't freak out.

If you'd like a hand taking care of the big rocks, being proactive, and not freaking out, apply to work with me below.

Free Assessment Form

Best,

John

Sources:

Cancer detection rate (1 to 1.6%) and the findings cascade

Incidental findings (78–97%) and false positives

Overdiagnosis, length-time and lead-time bias

The South Korea thyroid screening example (15-fold, no mortality drop)

No society recommends it / no RCTs (the Davenport & Reeder viewpoint)

The social media hype gap (87% positive, 15% mention harms)

  • Original study: Nickel B, Moynihan R, et al., "Social media posts about medical tests with potential for overdiagnosis," JAMA Network Open, 2025 (doi:10.1001/jamanetworkopen.2024.61940), reported via Diagnostic Imaging (link above).

Company self-reported numbers

Pricing ($499–$2,499)

Vinay Prasad's argument

The Joe Amabile hook

Your longevity checklist numbers

Best,

John

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John Solokas https://www.solokasfocus.com
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