Before we dive in … Day 2 …
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A few weeks ago, I visited my parents. My dad told me he thought I looked good.
“Have you lost weight?” he said. “What are you now, 150?”
This was one of those funny moments where guessing wrong kind of undermines the compliment. Yes, I have lost a lot of weight — but I haven’t been 150 pounds since probably 8th grade.
Saying that I was down to around 170 sounded a bit underwhelming by comparison — even though I’m proud of what I’ve done.
It’s one thing when your dad guesses your weight wrong, but it’s another thing entirely when your doctor makes a similar mistake — or for that matter, perhaps, if we were to learn that an entire, commonly used but oft-maligned metric might also be getting things wrong.
That’s exactly what’s been happening with the way medical professionals calculate body mass index (also known as BMI), at least if a new study is accurate.
BMI is simply your weight divided by your height squared, so it should be pretty hard to mess up.
But, by definition it doesn’t break down how much of your weight is fat, or where that fat is located in your body, nor does it distinguish between a person who is 200 pounds of muscle and a person who is 200 pounds with very little muscle.
Doctors and fitness professionals have been saying this for decades, but the metric has persisted — in clinical care, in insurance underwriting, in public health policy — largely because it’s free, fast, and requires nothing more than a scale and a tape measure.
The new study, published in the journal Nutrients and being presented at the European Congress on Obesity next month, put that persistence to the test.
Researchers took 1,351 adults — ages 18 to 98 — and compared their standard WHO BMI classifications against their actual body fat, measured using DXA scanning.
DXA, or dual-energy X-ray absorptiometry, is the gold standard for measuring body composition, because it directly measures fat, muscle, and bone. The findings:
Among people BMI labeled as overweight, more than half were in the wrong category when measured by actual body fat — and of those, roughly three-quarters turned out to be normal weight.
Among people BMI labeled obese, about one in three was actually only overweight. And among people BMI labeled underweight, two-thirds were actually normal weight.
Overall, more than one-third of adults in the study were placed in the wrong weight category entirely.
Caveats:
The sample in this study was entirely White Caucasian adults in northern Italy, and the researchers cite this as a limitation, since BMI is already known to perform differently across ethnic groups.
Also, overall rates of overweight and obesity in societies look similar whether you use BMI or DXA at the population level; the researchers say that’s because mismatches for individual people might cancel each other out in the aggregate.
All of this comes at a remarkable moment in weight medicine.
GLP-1 drugs like Ozempic and Wegovy have upended how millions of people think about and pursue weight loss.
Employers are grappling with whether to cover them, insurers are drawing eligibility lines, and doctors are deciding who qualifies.
Many of those decisions flow, directly or indirectly, through BMI.
If the tool getting used to make those calls is wrong for more than one in three of the people it touches, that’s a big problem.
Ironically, we’re still figuring out the full size of a problem that’s entirely about measuring size.
Other things worth knowing …
NPR, CNN: Virginia took a step on Tuesday to counter and possibly surpass President Trump’s national effort to redraw congressional voting maps in favor of the GOP as voters narrowly approved a Democratic-backed constitutional amendment to sideline let lawmakers directly implement a new map.
The Athletic: FIFA is considering asking President Donald Trump for a full moratorium on ICE raids across the United States during the World Cup this summer. European nations also privately relayed concerns from their fans about potential ICE activity during the tournament.
The New York Times: The F.B.I. began investigating a New York Times reporter after she wrote a story about Director Kash Patel using bureau personnel to provide his girlfriend, Alexis Wilkins, with government security and transportation. Some Justice Department officials saw the inquiry as retaliation for an article that Mr. Patel and his girlfriend did not like. It was determined there was no legal basis to proceed with the investigation.
The Independent: Tucker Carlson, increasingly at odds with Trump over the Iran War, has expressed buyer’s remorse over his role in getting the president elected. “Millions of people like us are the reason this is happening right now,” the former Fox News star said, adding: “[W]e’re implicated in this for sure ... We’ll be tormented by it for a long time. I will be. And I want to say I’m sorry for misleading people.”
Futurism: Chinese Workers Horrified as Bosses Direct Them to Train Their AI Replacements: Why would they choose to dig their own graves?
WSJ: More young Americans are turning to trade school to pursue in-demand jobs like plumbing and electrical work but encountering something they didn’t expect: hefty price tags. Nationwide, trade and technical school revenue hit $5.1 billion in the last quarter of 2025, up 41% from four years before that, according to federal data.
NBC News: Elizabeth Smart is adding a new title to her résumé: bodybuilder. The 38-year-old Smart — whose terrifying abduction story is told in the 2025 Netflix documentary, “Kidnapped: Elizabeth Smart”— revealed the career pivot with a picture of herself on Instagram from a recent bodybuilding competition: “This was a big change for me, it was hard, it pushed me, challenged me not to give up. I am so proud of myself for doing this. I am so proud of my body, and I want to celebrate it,” she wrote.
Thanks for reading. Photo by Alex Engelman on Unsplash. I wrote about some of this before at Inc.com. See you in the comments.
Another guideline that's probably better than BMI, but not the DXA scanning, your waist circumference should be half your height.
As for the GLP-1 drugs, studies seem to show if you stop taking the drug, you will regain the weight you lost.
I’m sure the only reason to add the instagram photo of Elizabeth Smart to the newsletter was to comment about the accuracy of her BMI. Did I miss something?