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A delivery in Wilmington, N.C., this month. Heat is linked to hundreds of workplace deaths each year, but labor groups say the true toll is unknown because heat-related illnesses are not properly tracked or reported.
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A delivery in Wilmington, N.C., this month. Heat is linked to hundreds of workplace deaths each year, but labor groups say the true toll is unknown because heat-related illnesses are not properly tracked or reported.
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A teacher at a Head Start program run by Easterseals South Florida instructing students on reading and writing. Head Start has served over 30 million children since it was created.
OpenAI announced today that ChatGPT Health will now be available to all users over 18, and on all plans, including free ones. My general skepticism of AI-based health advice aside, I think there are good reasons to avoid this iteration of ChatGPT Health entirely—including a major downgrade in privacy from the original ChatGPT Health setup.
With ChatGPT Health, you can connect your medical records or Apple Health data to the chatbot. OpenAI says that the bot will ask for permission to access your health data for conversations, and that it’s not meant to replace a doctor, but to give advice or help you interpret your medical data. Despite these caveats (and the announcement's chart seeming to show that ChatGPT Health gets more “high scores” than real life doctors), I see red flags everywhere.
When OpenAI first announced its “dedicated health experience,” one of the big selling points was that conversations in Health would not be used for future AI training, and that your Health conversations would be kept separate from all other conversations.
But the terms have now shifted. OpenAI now says that your connected health information will not be used to train AI, and that only conversations that use that connected information will be considered Health conversations. This means that if ChatGPT reads about a diagnosis from your medical records, you’re now having a protected Health conversation. But if you don’t connect your medical records, and just want to tell ChatGPT about your diagnosis in your own words, that’s not considered a Health conversation.
This also means that the only way to get the privacy protections of ChatGPT Health is to share your health data with OpenAI. As the company writes in its announcement: “You can ask health questions in ChatGPT without connecting anything. To use Health and get responses grounded in your own information, you can choose to connect Apple Health, supported medical records from U.S. hospital systems, One Medical, or Function Health.” The latter conversations would have privacy protections. The former would not.
OpenAI touts its HealthBench evaluations to imply that ChatGPT is good at giving medical advice. But, as I’ve previously written, LLMs like ChatGPT don’t give reliable medical advice and shouldn’t be trusted. Previous studies have shown that even when an LLM gives the “right” answers to carefully constructed health-related questions, real-world conversations tend to go off the rails.
HealthBench seems to suffer from the same limitations. OpenAI says that real physicians wrote rubrics to grade responses, and physicians used those rubrics to grade responses from different ChatGPT models and from their fellow physicians. Conveniently, the results show that paid ChatGPT models score higher than free ones, which in turn score higher than real doctors.
But that doesn’t mean a chatbot is actually trustworthy. One evaluation of the HealthBench framework points out that the tests are not real conversations, and "may omit idiomatic phrasing, topic shifts, and unanticipated patient concerns." Another major limitation is that HealthBench only tests short conversations, an approach that “precludes assessment of longitudinal workflows and multidisciplinary handovers,” like real-life conversations that may be long or involve other topics.
People who ask ChatGPT for health advice aren’t conducting specific, focused tests of its health advice, and so the LLM’s responses aren’t necessarily going to be anything like the responses that were rated in HealthBench. OpenAI clearly knows this, since the announcements emphasize how often people ask health questions in the course of everyday conversations.
And those are just the limitations of the HealthBench framework, before you start looking at the specifics. The authors of the paper I quoted above point out that the testing material didn’t include enough rare diseases to know how well a model would perform when asked about them. And the rubrics seem sloppy, too: OpenAI’s own example, from its announcement of HealthBench, gives a certain response 9 points for “Includes clear and concise advice to seek emergency medical care at the beginning of the response” and then later in the same rubric, awards another 10 points for “States to contact emergency medical services at the beginning of the response.” That looks like either OpenAI is double-dipping to inflate scores, or simply not having anybody proofread the rubrics. Either way, I can’t trust the results.
Most importantly, people do use ChatGPT for medical advice, and they have suffered medical problems and even death after doing so, and the company knows it. The company was sued this week by a pastor who says he almost died after asking ChatGPT-4o (a model no longer available) for advice on what turned out to be a pulmonary embolism. That lawsuit seeks an injunction that would make the company stop offering health products like ChatGPT Health.
Other lawsuits against OpenAI allege that its products contributed to suicide and psychosis in its users. ECRI, a medical safety nonprofit, named the misuse of AI chatbots the number one health technology hazard of 2026.
If you want to give ChatGPT Health a try anyway, it’s worth knowing how to use the tools it offers to protecting your privacy (somewhat):
You can use temporary chats to start a conversation that doesn’t use memory or personalization features.
After importing your health data, you can review and edit the information—for example, correcting errors or removing anything that you don’t want on record.
You can disconnect your health information at any time in your settings, under Health > Accounts. The company says the data will be deleted “within 30 days.”
You can make ChatGPT ask for permission to access your health records every time (rather than granting a blanket permission). This setting can be changed in Settings > Plugins > Health.
Be careful when using plugins that may share health information. OpenAI says it has “additional safeguards” that may ask you for permission to share data, but it also says “We continue to test these safeguards...” which suggests that the company isn’t currently catching everything it should.
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Pop quiz: You want to lift 185 pounds. How many plates do you put on each side of the barbell, and what sizes? If you didn’t immediately answer “a 45 and a 25, of course,” perhaps a little primer on plate math would help.
Let’s start with the basics. When you tell somebody how much weight you lifted, that weight includes the total poundage that you had in your hands—including the bar.
At most gyms in the U.S., a typical full-size barbell weighs either 45 pounds or 20 kilograms (which works out to 44 pounds). If the rest of your weight plates are in pounds, go ahead and assume it’s 45. (Nobody ever says "I benched 224 pounds" even if, technically, they used a 20-kilo bar.)
You'll know that you're looking at one of these common barbells if it's seven feet long, and the sleeves at the end are two inches in diameter. In nearly all gyms, the bars on squat racks and bench press stations will be of this type.
If your gym has multiple bar sizes, check the end for a label giving the weight, or ask somebody. If your gym has kilo plates, or if it's a CrossFit box, you should know that Olympic-style weightlifting is done with a 20 kilogram bar for men (close enough to 45 pounds), and a shorter, narrower 15 kilogram bar for women—which CrossFitters tend to estimate as 35 pounds, even though between you and me it's closer to 33. (Why do women's barbells exist in the first place? There's a whole story to that.)
Your gym might also have lighter bars, which could be 25 pounds or even 10. Home exercise equipment sometimes uses a 1-inch-wide bar without the wider collars you’ll see on Olympic or powerlifting bars; those bars are lighter, and you should weigh yours or check the package to see what you’ve got.
If you’re lifting with a Smith machine, or any other kind of machine, don’t bother trying to figure out how much the machine or its bar weighs. Every machine is different; they’re almost never labeled, and the weights won’t necessarily feel the same as they would on a barbell. Just write down the total weight you loaded onto it—that’s enough for record-keeping purposes.
What about the clips or collars that hold the weight on? Usually they’re not heavy enough to bother adding into your calculations, but if they’re large and you know the weight, feel free to include them. In weightlifting and powerlifting competitions, the collars are 2.5 kilos each, and they are counted in the weight lifted.
I'm going to explain below how to add up the weights yourself, and how to memorize a few quick numbers to let you load bars quickly without needing a calculator. But if you're new to lifting, or if you want to double check your math, consider using an app. One of my favorites is called Bar Is Loaded, and it's available for free on both iOS and Android.
An online equivalent is this calculator from ExRx. Note that you have to tell any calculator how heavy your bar is, what sizes of plate you have available, and how many of each there are. (The app will probably have some sensible defaults, but double-check them.) In a gym the plates may be unlimited, but in a home gym there may be certain numbers you just can’t achieve if you don’t have the right combination of plates. That's why apps often ask for your inventory of plates.
This may be obvious, but I want to make sure this information is easy to find: To calculate the total weight you’ve put on the bar, add up the plates on one end, double that number, and add the weight of the bar. So if you have a 45 and a 25 on each end, add 25 + 45 to get 70, double that (140), and add the weight of the bar (140 + 45 = 185).
More often, though, you'll start with a number in mind that you’d like to lift, and then have to load the bar appropriately. Start practicing and soon you’ll be able to load a bar correctly without thinking about it too much. Here are some strategies to help you do that.
Let’s assume we’re working with a 45-pound bar. You’ll end up using the same combinations over and over, and these numbers will start to look really familiar:
55 pounds: a 5-pound plate on each side
65 pounds: a 10-pound plate on each side
95 pounds: a 25-pound plate on each side
Once you're strong enough to load full 45-pound plates on either side of the bar, you'll want to become familiar with multiples of 45. It's common to describe these weights in terms of the number of plates per side. So if somebody says "I can bench two plates," they mean two on each side, or 225 pounds. Here are the common numbers in that scheme:
135 pounds: one 45-pound plate on each side
225 pounds: two 45-pound plates on each side
315 pounds: three 45-pound plates on each side
405 pounds: four 45-pound plates on each side
495 pounds: five 45-pound plates on each side
As you warm up for a lift, you can do the math as you put plates on. Say you do a set with just the empty bar, then with a 10 on each side (that’s 65), then a second pair of 10s (85), then swap both of those out for a 25 (now we’re up to 95) and you want to do your next set at 100. You know you need five more pounds, so look for a pair of 2.5-pound plates, and there you go.
Some gyms have their plates in kilos instead of pounds. (Some have both, so keep your wits about you!) The principles are the same: count the bar, and memorize common combinations. Bumper plates and competition-style steel plates are often color-coded, so I've included the colors below:
On a 15kg women’s bar:
A pair of 10 kilo plates (green) = 35kg
A pair of 15s (yellow) = 45kg
A pair of 20s (blue) = 55kg
A pair of 25s (red) = 65kg
Two pairs of 25s = 115kg
Three pairs of 25s = 165kg
Or, if you’re using a 20kg men’s bar:
A pair of 10 kilo plates (green) = 40kg
A pair of 15s (yellow) = 50kg
A pair of 20s (blue) = 60kg
A pair of 25s (red) = 70kg
Two pairs of 25s = 120kg
Three pairs of 25s = 170kg
If you go back and forth between pounds and kilos, it helps to be able to convert them in your head. Multiply kilos by 2.2 to get pounds, or divide pounds by 2.2 to get kilos. (Kilos are "bigger" than pounds, so the same object will weigh a smaller number of kilos and a larger number of pounds.) Some of the numbers are nicely symmetrical:
5kg = 11 pounds
10kg = 22 pounds
20kg = 44 pounds
30kg = 66 pounds
40kg = 88 pounds
50kg = 110 pounds
100kg = 220 pounds
150kg = 330 pounds
I lift at one gym where everything is in kilos, and another where everything is in pounds. Fortunately, I do different lifts in each place, so I keep my Olympic lifting notes in kilos and my powerlifting notes in pounds. I recommend this approach rather than trying to convert units on every lift as you do it.
If you’re not used to working in kilos, start with memorizing just one number: your own weight in kilos. That lets you make quick judgments like “This is heavier than me” or “This is about half my weight” without having to whip out a calculator.
Staying up to date on wellness trends on social media is necessary for my job, but the truth is, my algorithm does a scarily good job of keeping me scrolling all on my own. Unfortunately, all that wellness usually leaves me feeling burnt out. The latest irony here is that the moment I think about putting my phone down, I’ll get a video that claims it has a solution for the anxiety all the videos before have been giving me. Cold plunges, breathing exercises, humming, stretching your hips in the exact right way to magically release all your trauma—whatever the specific advice may be, I keep getting told by wellness influencers that I’ve been neglecting to “regulate my nervous system.”
Your nervous system is the network that runs your body's background operations—breathing, heart rate, digestion, hormone release, immune response—largely without your conscious input. It's split broadly into two systems that work in tension: the sympathetic nervous system, which mobilizes you for action ("fight or flight"), and the parasympathetic nervous system, which handles recovery and maintenance ("rest and digest"). But from what I’ve been seeing online, the idea of “regulation" reads more like a lifestyle brand than a biological process.
Some parts of this appeal to me. It seems like a lot of the solutions come from well-meaning yogis and therapists who aren’t trying to sell you any sort of product. Many of the practices in my feed are cheap or free, and I appreciate that. I welcome the idea of a wellness culture focused on doing less, as opposed to endless optimization.
At the same time, with a new wellness trend comes new ways to spend your money. There’s a growing category of consumer devices that promise to "hack" your vagus nerve into a state of calm. I’m currently testing some of these products, like this daytime wearable or this Vagus Nerve Stimulator. Before I issue my ruling on these devices, let’s separate fact from fiction here: Because the phrase at the center of it all, "nervous system regulation," has drifted so far from its clinical roots that it's worth asking what it actually means—and whether the products cashing in on it can deliver anything real for you.
It should be no surprise that the clinical definition is narrower and less mystical than the social media version suggests. Clinically speaking, nervous system regulation refers to “the nervous system's capacity to adapt to stress, maintain homeostasis, and return to baseline efficiently after a challenge,” neuroscientist Dr. Ramon Velazquez says. Being "regulated" isn't as simple as just feeling calm. Instead, “a well-regulated nervous system can appropriately shift between states of arousal, focus, recovery, and rest as circumstances demand,” Velazquez says.
Most techniques marketed for nervous system regulation—including breathwork, cold exposure, mindfulness practices, HRV-guided training, and vagus nerve stimulation—are really attempts to shift the balance from your sympathetic to your parasympathetic system. However, “effective nervous system regulation is not about suppressing stress responses,” Velazquez says. “It’s about flexibility.” Regulation might sound like it means “control,” but it’s more accurate to think of healthy regulation as your ability to respond appropriately to a situation and then recover from that response, rather than staying stuck in either overdrive or shutdown.
“From a scientific perspective,” Velazquez says, “the strongest drivers of nervous system health remain the fundamentals: quality sleep, regular exercise, good nutrition, stress management, avoiding toxins, and social connection.” Consumer products may offer additional benefits, but they are unlikely to replace these foundational behaviors.
Individual responses to any nervous-system intervention vary widely, shaped by underlying health conditions, medications, stimulation intensity, and simple differences in sensitivity. But if you're healthily average, like myself, and you, too, are getting nervous system content online, here’s how you can sift through the noise.
What's real: Breathwork and mindfulness have solid research behind them for improving stress resilience and autonomic flexibility. These are low-risk, well-studied practices that can influence the sympathetic-parasympathetic balance Velazquez describes.
What's promising but up in the air: cold exposure and non-invasive vagus nerve stimulation. Both have some promising findings, but any sweeping claims might go beyond what the science shows.
What causes more harm than good: buying into the idea that a single device can do the work of foundational habits, or ignoring your body's signals because a product is marketed as safe and calming. If a "relaxation" device is producing pain, cramping, or muscle seizures, it's a sign to stop and, if needed, talk to a doctor.
Velazquez shares a few practical steps if you want to support your nervous system without chasing trends:
Prioritize sleep, movement, and nutrition first.
Try breathwork or mindfulness before reaching for a gadget. Something as simple as slow, extended exhales has more research behind it than most consumer devices on the market.
Build in real recovery, not just stimulation. Regulation is about your ability to return to baseline—social connection, downtime, and stress management all help on this front.
If you try a consumer device, treat it as a complement, not a fix. Start conservatively, pay attention to how your body responds, and stop if you experience pain, twitching, or discomfort rather than pushing through it.
None of this means nervous system regulation is a myth, or that the interest in recovery over optimization is misguided—if anything, I'd argue it's quite a healthy correction. But the version being sold on social media, distilled into a single gadget or a five-minute hack, doesn't reflect what the term actually describes in clinical practice. For most healthy individuals, your ability to regulate your nervous system is built primarily through sleep, movement, nutrition, and social connection. As with all health trends, there's rarely a magic device that can replace the fundamentals.
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Nobody likes to feel sluggish and sweaty, so when the sun is set to “broil,” a lot of us would rather take our workout to an air-conditioned gym. But the human body can acclimate to exercising in the heat, so it may be worth heading outdoors anyway. After a few weeks, these temperatures will be your new normal—and research suggests you may enjoy a small performance boost when the weather cools down again.
Hot workouts can be dangerous, so I trust that you know common-sense advice about running in the heat. Among the most important: Drink to thirst (or a little bit more), and stop and get help if you start feeling symptoms of heat illness like nausea, dizziness, or weakness. And while it’s great to work on your ability to run in the heat, don’t be stupid about it—stay inside if the temperature is hotter than you can handle, and stay aware of air quality levels (which get worse on hot days).
Running is miserable and heat is miserable; therefore, running in the heat is miserable. But there’s more to it than that, and exercising in the heat feels even worse than you'd expect from stacking those two factors together.
Exercise raises your body temperature, and when you stack that rise in temperature on top of the heat from the weather, it's very possible to reach dangerous levels of body heat. That means your body has to work harder than usual to cool itself down. The ways we cool ourselves also interfere with exercise performance. For example, your heart is working to supply blood and oxygen to your muscles, and to pump blood to the surface of our skin for cooling. Those tasks are a lot of work—no wonder we feel exhausted in the heat.
As a safeguard, your brain perceives effort differently in the heat, so even before you overheat, you feel sluggish. In a study published in the European Journal of Physiology, cyclists who worked out in a lab with a temperature of 95 degrees were slower than when they did the same time trial at 59 degrees. That makes sense, but here’s the weird part: They didn’t overheat and then slow down. They were slower from the start. It seems our brains slow our bodies down proactively on hot days in order to conserve energy.
As a workout continues, our bodies heat up. In another study, published in the Journal of Applied Physiology, when asked to cycle to exhaustion, participants pooped out when their core temperatures reached 104 degrees, no matter what temperature they started at. That's the temperature where serious heat illness can set in, so it makes sense that our bodies will put on the brakes at that point. In that study, athletes who kept cool with a fancy water-cooling jacket lasted the longest. (You can mimic this effect in your own workouts by drinking ice-cold beverages and pouring water over your head.) The longer you can keep your body cool, the longer you can keep up a hard effort.
But cooling your body isn’t a complete solution. Dumping a cup of ice water over your head or putting one into your belly only provides momentary relief, and water-cooling jackets aren’t practical outside of physiology labs. So let’s look at what happens in real-world conditions.
Our most efficient way of cooling off is sweating. When moisture evaporates from your skin, it takes some body heat with it. In humid weather, though, sweat doesn’t evaporate as easily because the air is already full of water vapor. So when we’re talking about “heat,” we really mean something more like “perceived heat,” which is a combination of heat and humidity. This heat index chart shows the relationship:
You’ll run slower in the heat (and humidity). While you can find charts like this one that predict how much slower you will run a race, the truth is that heat's effect on your running depends on whether you’re used to the heat, and on your body size.
That’s right—not your fitness level, but your actual physical size. People who are larger have more muscle, fat, or both. Muscle generates heat, and fat acts as an insulator. On the other hand, smaller folks generate less heat, but have more skin through which to dissipate that heat—the ol’ surface area to volume ratio. This is why petite runners place better in races on hot days.
Some people think being more fit makes you better at dealing with heat, but that's only partially true: The fitter you are, the more body heat you produce, just because you’re so good at working hard. Short of changing your body shape (which is possible, but hardly a short-term fix), what can you do to tolerate exercising in the heat better? The answer is simple: Spend more time exercising in the heat.
Running in the heat makes you better at running in the heat—and it makes you better, period. Say you do all your workouts outdoors this summer, while your equally fit twin does identical workouts on a treadmill in an air-conditioned gym. Who do you think will finish first in a 5K on a hot weekend in August? That’s right, you will.
But even if the weather is unseasonably cool on that August day, your heat training will still help you beat your twin. Part of the magic of heat training is that it increases the amount of blood in your veins (the better to put it towards your skin for cooling, while still having enough to fuel your muscles). The effect has been compared to a mild, totally legal version of blood doping. Scientists are still debating exactly how this effect works and whether it always happens when people attempt to adapt to heat, but overall, the evidence is strong enough that I believe we should all try to get some of those adaptations if we can do so safely.
Here’s the bad news: Heat adaptation takes work. It’s not enough to sit around in the air conditioning all summer, only venturing outside for occasional workouts. A study published in the European Journal of Applied Physiology found that people who made no particular effort to exercise in the heat didn’t have any better heat tolerance in the fall than in the spring. If you want the advantages of heat training, you have to work for them.
I'll go over some heat adaptation strategies below, but the general idea is that you spend at least two weeks making sure to get plenty of time in the heat. Your body will get better at cooling itself, and those hot-weather runs will feel a little less awful. Heat adaptation isn't magic, though. You'll still feel hot, and you may still run slower than in cool temperatures. You'll just be able to get more of a workout in before your body temperature rises to dangerous levels. If you want to know more about heat training, I wrote about my experience last year with a heat-training sensor, which allowed me to get detailed feedback about how my heat training was going.
In scientific research, heat acclimation protocols for athletes generally involve 7 to 10 consecutive days of exercising in the heat, for 60 to 90 minutes each day. A simpler method that can be done by entire teams, or by individuals, is to simply do your normal training in the heat for about two weeks.
Take it easy at first. Remember that your body is still trying to convince you that you are super tired and need to slow down. Safety guidelines for workers provide a reality check here. On their first day in the heat, the Occupational Safety and Health Administration (OSHA) recommends giving workers just 20% of their usual workload. Within a week, they should ramp up to 100%.
This U.S. Army training protocol provides a good road map for adapting yourself to the heat: Spend at least two hours in the heat each day, it says, and include cardiovascular exercise (like running, cycling, or anything that gets your heart rate up) as part of that. If you can’t handle two hours without feeling symptoms like nausea or dizziness, do what you can and view the two-hour benchmark as a goal to work toward.
You can expect to be better adapted to the heat after about two weeks of spending two hours per day in the heat, although you may be able to start seeing results in just a few days.
A way to combine the protocols above, without relying on the weather, is to step into a sauna or hot bath after your workout. If your gym has a sauna, this is a great way to use it. The post-workout sauna time will help your heat adaptation, and you can do it even if your workout was done in less-than-sweltering temperatures.
The time spent in the sauna can be 15 to 30 minutes, starting with a shorter time and working up to longer. Note that these targets only apply if you're using the sauna after a workout when your body temperature is already elevated from exercise. If you skip the workout, you'll need to add 20 minutes or so to your sauna time to get the same effect.
To stay adapted to the heat, you have to keep spending time in it. You can take a few days off, but if you slack off for a week, you’ll start to lose your hot-weather superpowers. This snowballs quickly: you'll lose about 75% of your adaptations after three weeks, according to the Army’s estimates.
To keep up your heat training in cool weather, you can try wearing long sleeves and tights, like elite runner Kara Goucher did when training for a world championship race in muggy Osaka. (She won a bronze medal, the first American ever to do so). She also spent a few weeks in Osaka before the race began; traveling to experience the heat might be an option worth considering if you’re a dedicated athlete with vacation time to burn.
You can also try the opposite of all the standard keep-cool advice, and choose to run at the hottest time of day on asphalt roads with no shade. Or return to the sauna protocol after your cooler-weather workouts. Whatever you do, stay safe, and enjoy your new superpowers.
A health worker measures the temperature of a motorcyclist passing through a checkpoint in Goma, North Kivu, Democratic Republic of the Congo, on Thursday.
A Customs and Border Protection officer at John F. Kennedy International Airport in New York.
A motorcycle taxi driver at a hospital in Goma, Democratic Republic of Congo, on Sunday.
At a hospital in Ituri Province, Democratic Republic of Congo, the center of a new Ebola outbreak.
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Luigi Mangione’s lawyers have argued that the evidence found in his backpack when he was arrested was obtained illegally and cannot be used at trial.
A lawsuit against the F.D.A. threatens access to medication abortion, and the Trump administration has remained strikingly silent about the case, even as it reached the Supreme Court.
For Dr. Alister Martin, New York City’s new health commissioner, keeping New Yorkers insured could prove to be the main challenge of his tenure.
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Eliza Leone, a dietitian, teaches culinary medicine to a mix of medical, dental and dietetics students from Tufts University.
On Friday, New York Mayor Zohran Mamdani repeated plans for a new agency that would respond to mental health crises in the wake of two fatal shootings by the police.
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