Body mass index (BMI) may not be the most accurate predictor of death risk.

A new study from the University of Florida found that BMI — a measurement that is commonly used to determine whether a person’s weight is in a healthy range for their height — is “deeply flawed” in terms of predicting mortality.

Instead, one’s level of body fat is “far more accurate,” concluded the study, which was published this week in the Annals of Family Medicine.

BMI IS WRONG WAY TO MEASURE OBESITY, RESEARCHERS SAY

To measure participants’ body fat, the researchers used a method called bioelectrical impedance analysis (BIA), which uses a device to measure the resistance of body tissue to a small electrical current.

Over a 15-year period, those who had high body fat were found to be 78% more likely to die than those who had healthy body fat levels, researchers found.

They were also more than three times as likely to die of heart disease, the study noted. 

BMI — which is calculated by dividing weight by height, squared — was described as “entirely unreliable” in predicting the risk of death over a 15-year period from any cause.

The study included 4,252 people in the U.S. and pulled data from the National Health and Nutrition Examination Survey.

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BMI should not be relied upon as a “vital sign” of health, according to senior author Frank Orlando, M.D., medical director of UF Health Family Medicine in Springhill.

“I’m a family physician, and on a regular basis, we’re faced with patients who have diabetes, heart disease, obesity and other conditions that are related to obesity,” Orlando said in a press release for the study.

Over a 15-year period, those who had high body fat were found to be 78% more likely to die than those who had healthy body fat levels, researchers found. (iStock)

“One of the routine measures we take alongside traditional vital signs is BMI. We use BMI to screen for a person having an issue with their body composition, but it’s not as accurate for everyone as vital signs are,” he added.

BMI has been the international standard for measuring obesity since the 1980s, according to many sources, though some experts have questioned its validity. 

“I think the study shows it’s time to go to an alternative that is now proven to be far better at the job.”

An individual is considered obese if their BMI is 30 or above, overweight if it is between 25 and 29.9, of “normal” weight in the range of 18.5 to 24.9, or underweight if lower than 18.5.

While BMI is easy to calculate, one of its main limitations is that it cannot distinguish between muscle and fat mass, the researchers noted.

“People who are bodybuilders can really elevate their body mass index,” one doctor said. “But they’re healthy even with a BMI indicating that they’re obese.” (iStock)

“For example, people who are bodybuilders can really elevate their body mass index,” Orlando said. “But they’re healthy even with a BMI indicating that they’re obese.”

“BMI is just so ingrained in how we think about body fat,” Mainous added. “I think the study shows it’s time to go to an alternative that is now proven to be far better at the job.”

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Other methods, such as a DEXA (dual-energy X-ray absorptiometry) scan, may be even more accurate than BIA, but are much more expensive and not as accessible, the researchers noted.

“If you talk to obesity researchers, they’re going to say you have to use the DEXA scan because it’s the most accurate,” Mainous said in the release. “And that’s probably true. But it’s never going to be viable in a doctor’s office or family practice.”

“It has been an easy measurement tool that helps us understand at-risk groups across various populations and demographics, but it doesn’t provide accurate data from patient to patient,” a doctor said of BMI. (iStock)

Dr. Stephen Vogel — a family medicine physician with PlushCare, a virtual health platform with primary care, therapy and weight management options — echoed the limitations of BMI.

“It has been an easy measurement tool that helps us understand at-risk groups across various populations and demographics, but it doesn’t provide accurate data from patient to patient,” the North Carolina-based doctor, who was not involved in the study, told Fox News Digital.

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“These findings don’t challenge the assumptions about BMI — they strengthen the message that new standards, delivered in a consistent and low-cost way, would provide better nuance for the individual when it comes to their overall physical health.”

Potential limitations

“The main strengths of this study are a better correlation to an individual’s risk of morbidity and mortality — however, the limitations lie in the fact that we don’t have enough data to determine the right cutoff for these numbers, or to identify the right tools that will be both accurate and precise across the population,” Vogel said.

The researchers also acknowledged that body fat percentage thresholds haven’t yet been as standardized as BMI and waist circumference.

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Also, the age range of the participants in the study was limited by the data source.

“Future studies should extend this comparison of body fat to BMI in older adults,” the researchers wrote.

“These data will drive better discussions in the doctor’s office, as well as public health initiatives with the goal of improving the health of all,” a doctor said. (iStock)

The study was also limited by focusing only on mortality as an outcome, they noted, without taking into account any developing diseases — such as heart failure or cancer — that could deepen the understanding of body fat as a risk factor. 

The goal, according to Vogel, is to have a cost-effective, consistent method that can be used across the population with reliable accuracy.

“These data will drive better discussions in the doctor’s office, as well as public health initiatives with the goal of improving the health of all.”

“Benefits would come in the form of a more detailed list of information that helps providers and patients make informed decisions about the patient’s health, which is ideal,” Vogel noted.

“I’m hopeful there’s enough buzz around these measures that steps will continue to be taken toward regular implementation.”

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The researchers are hopeful that once standards are validated, measuring body fat percentage with bioelectrical impedance analysis could become standard of care. 

They added, “These data will drive better discussions in the doctor’s office, as well as public health initiatives with the goal of improving the health of all.”

Summer heat has swept the U.S., with warnings issued across the East Coast and Midwest.

In addition to putting stress on the body, hot weather can also take a toll on the brain and mental health.

Dr. Jace Reed, director of emergency psychiatry at Cedars-Sinai Hospital in Los Angeles, emphasized in an interview with Fox News Digital that the brain is a major organ that can be greatly affected by heat.

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Extreme heat can cause mental health changes like increased irritability and anxiety, along with decreased memory, attention and reaction time.

This can affect daily interactions socially and professionally, the expert cautioned.

“You may be slower at completing your task or remembering what someone just told you,” he told Fox News Digital. “Those can be initial early signs that the heat is affecting your brain and your mental abilities.”

Symptoms like extreme confusion could mark the beginning of a heat stroke, which could require hospitalization, the psychiatrist warned.

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In a separate interview with Fox News Digital, Thea Gallagher, a doctor of psychology and director of wellness programs at NYU Langone Health, noted that when the body overheats, it struggles to regulate internal balance.

This can lead to disrupted sleep, fatigue and poor concentration, as well as impaired cognitive function, slow reaction times and struggles with decision-making.

Extreme heat can cause slower cognitive function, along with delays in reaction times and decision-making. (iStock)

The heat can also increase oxidative stress and inflammation in the brain, Gallagher added, which can potentially damage neurons, worsen existing neurological conditions and raise stroke risk.

“Heat exposure may trigger an inflammatory response in the brain,” she said. “In cases like heatstroke, inflammation is believed to contribute to symptoms such as confusion and delirium.”

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Excessive heat can also weaken the protective blood-brain barrier, according to the expert, which makes the brain more vulnerable to toxins and pathogens.

Higher temperatures are also associated with disturbances in mood and violent behavior, especially during prolonged heatwaves.

Emergency visits for mental health concerns rise during hotter days, according to experts. (iStock)

Psychiatric emergency visits for anxiety, depression and substance use also rise significantly on the hottest days, Gallagher confirmed.

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Below are some of the main mental symptoms that can worsen in hot weather, experts cautioned.

• Irritability, anxiety or mood swings
• Difficulty concentrating, or “brain fog”
• Increased impulsivity or aggression
• Worsening of psychiatric symptoms like depression or psychosis
• Confusion or delirium, particularly during heat stroke

People who suffer from mental health conditions such as mood disorders, schizophrenia, anxiety or even dementia are more vulnerable in hot weather.

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Some psychiatric medications could make it difficult for the body to regulate temperature or stay hydrated, Gallagher noted, while heat can “intensify” symptoms like agitation or paranoia.

“People with cognitive impairments may not recognize the signs of overheating,” she added.

It’s important to have patience with yourself and others on hot days, one psychologist advised. (iStock)

“Some SSRIs (selective serotonin reuptake inhibitors) can suppress sweat production, which is the body’s primary cooling mechanism. This raises the risk of overheating, dehydration and even heat stroke.”

“Paradoxically, SSRIs can also cause excessive sweating in some individuals — a side effect known as ‘SSRI sweats,’” she went on. “While this might seem like it would help with cooling, it can actually lead to dehydration if fluid intake doesn’t keep up.”

Protecting brain health

The experts recommended the following practices to protect brain health in extreme heat.

• Stay hydrated, as dehydration worsens cognitive decline
• Avoid peak heat hours; stay indoors or in shaded areas from 11 a.m. to 4 p.m.
• Use fans, air conditioning or cool showers
• Use blackout curtains and cooling bedding to ensure restful sleep
• Ask your doctor if any medications may increase heat sensitivity
• Use deep breathing and relaxation techniques to help manage heat-induced stress
• Stay socially connected; check in with friends and family

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“Days are also longer and there are more activities, which can be exhausting,” Gallagher noted. “Therefore, it is good to prioritize sleep and rest … and [find] ways to slow down when you can.”

A vaccine ingredient is in the spotlight this week, as a preservative called thimerosal was included on the agenda for a meeting of the CDC’s Advisory Committee on Immunization Practices (ACIP).

“Presentation regarding thimerosal in vaccines” was listed as an agenda item for Thursday, June 26, followed by “Proposed recommendations regarding thimerosal-containing influenza vaccine.”

Thimerosal (also spelled thiomersal) is a mercury‑based preservative that has been used in multi-dose vaccines and medications since the 1930s as a means of preventing contamination, according to the CDC.

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The ingredient is intended to prevent contamination by stopping the growth of bacteria and fungi, the same source states.

Due to growing concerns about potential mercury exposure, the American Academy of Pediatrics, Public Health Service agencies and vaccine manufacturers agreed that thimerosal should be “reduced or eliminated in vaccines.”

In 2001, thimerosal was removed from all vaccines recommended for children 6 and younger — except for influenza.

Today, multi-dose flu vaccines still contain thimerosal, but other versions are available without the ingredient.

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At the June 27 meeting, the CDC’s Advisory Committee on Immunization Practices voted to recommend that all adults (including pregnant women) and all children 18 years and younger should receive seasonal influenza vaccines only in single-dose formulations that do not contain thimerosal, according to meeting notes published by the CDC.

The CDC’s Advisory Committee on Immunization Practices voted to recommend that all adults (including pregnant women) and all children 18 years and younger should receive seasonal influenza vaccines only in single-dose formulations that do not contain thimerosal. (iStock)

Despite these recommendations, the CDC and other health agencies have claimed there is no evidence that thimerosal poses health risks.

“Thimerosal use in medical products has a record of being very safe,” the agency’s website states. “Data from many studies show no evidence of harm caused by the low doses of thimerosal in vaccines.”

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Dr. Jacob Glanville, CEO of Centivax, a San Francisco biotechnology company, reiterated that American children have not been receiving thimerosal for over 20 years in their vaccines, but that it remains in some multi-use vial vaccines, mostly outside the U.S.

Today, multi-dose flu vaccines still contain thimerosal, but other versions are available without the ingredient. (Reuters)

“We support any effort to remove it entirely — there are other preservatives that are not based on mercury,” Glanville told Fox News Digital. 

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Glanville noted that his company’s vaccines never contain mercury, aluminum, formaldehyde, or pig- or cow-derived materials.

Illegal disposable e-cigarettes, also known as vapes, may present a greater danger than traditional cigarettes, according to a study from the University of California (UC) Davis.

The research, published in the journal ACS Central Science, found that hazardous levels of several toxic heavy metals in illegal vapes could present a high cancer risk.

Researchers used a special instrument to test the puffs from three popular vape brands — ELF Bar, Flum Pebble and Esco — that are not FDA-authorized for use in the U.S., but are widely sold by retailers.

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Three heavy metals — lead, nickel and antimony — were detected in all heavily flavored and lightly flavored devices that were tested. 

These metals are classified as carcinogens, potentially leading to various types of cancers, such as skin, lung and kidney, according to the National Institutes of Health (NIH). 

All vapors exceeded the cancer risk limits for nickel, which has been linked to cardiovascular disease, asthma, lung fibrosis and respiratory tract cancer, per NIH.

Brett Poulin, senior study author and assistant professor at the UC Davis Department of Environmental Toxicology, told Fox News Digital that he was shocked at the levels of toxic metals.

“When I analyzed the first samples, the lead concentrations were so high that I genuinely thought the instrument was broken,” he said. “The levels far exceeded anything in our past data, or even the published literature.”

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One of the brands tested exposes users to as much lead as smoking 19 packs of cigarettes, the researchers discovered.

Additionally, most of the disposable e-cigarettes tested in the study were found to contain greater levels of metals and metalloids than older refillable vapes.

After evaluating about a week’s worth of puffs, the researchers determined that lead, nickel and antimony were detected in all tested vapes. (iStock)

At one point, Poulin said, he physically opened a device and discovered that it was using leaded copper alloys, which are metals made primarily of copper with small amounts of lead.

“These materials leached dangerous levels of lead into the e-liquid, even without the device being used,” Poulin told Fox News Digital.

“It remains unclear whether this was an intentional design choice, a cost-cutting measure or a manufacturing oversight.”

“This neurotoxin poses serious health risks, particularly to children and adolescents.”

There is no known safe level of lead exposure, according to Poulin.

“This neurotoxin poses serious health risks, particularly to children and adolescents, who are especially vulnerable.”

Daniel Sterman, M.D., director of the Pulmonary Oncology Program at the NYU Langone Perlmutter Cancer Center, told Fox News Digital that the study “clearly” demonstrates high concentrations of metal.

Men were found to be more likely to vape than women, according to the CDC. (iStock)

“There are several health risks of vaping that we enumerate for our patients and their family members, [such as] risks of various lung diseases, including asthma, COPD and lung cancer,” said Sterman, who was not involved in the study.

The doctor noted that while it is challenging to establish a direct link of causation between disposable vapes and cancer, he does see cancer patients who use the devices.

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“Disposable vapes should be highly regulated by local, state and federal agencies, and restricted to those individuals 21 years or older,” Sterman recommends.

The doctor also called for the packaging on disposable vapes to clearly outline the many health risks, “particularly to teenagers and young adults.”

Potential limitations

One of the primary limitations of the study was that only three disposable e-cigarette brands were tested out of the hundreds currently on the market. 

There are distinct differences in the metal leaching and profiles across all three brands, Poulin shared. 

The Center for Disease Control (CDC) found that the percentage of adults who used electronic cigarettes increased from 4.5% in 2019 to 6.5% in 2023. (iStock)

“We still know very little about the metal content in the vast majority of untested disposable e-cigarette products,” he said. “This gap in knowledge poses a significant public health concern, especially given the popularity of these devices.”

A spokesperson for the China-based brand, ELFBAR, told Fox News Digital that they refute the results of the study, claiming that they stopped shipments in May 2023.

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Due to ongoing trademark litigation, they are unable to market or sell products in the U.S., the company stated.

“This market void has led to a surge in counterfeits, imitations and illicit variations misusing our brand name,” the spokesperson said. “As such, we have every reason to believe the devices tested in this study are not genuine and were not manufactured by ELFBAR.”

Many disposable vapes that are not FDA-authorized for use in the U.S. are widely sold by retailers. (Mike Kemp/In Pictures via Getty Images)

The spokesperson acknowledged that smoking remains the leading cause of preventable death and disease worldwide, noting that the recent study “continues to undermine public understanding of smoking cessation.”

The other two brands tested in the study did not respond to requests for comment.

“Disposable vapes should be highly regulated by local, state and federal agencies and restricted to those individuals 21 years or older.”

Electronic cigarette use among adults increased from 4.5% in 2019 to 6.5% in 2023, according to the U.S. Centers for Disease Control and Prevention (CDC).

Men are more likely to vape than women, while 15.5% of young adults between the ages of 21 and 24 reported using e-cigarettes, the above source states.

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The UC Davis study received support from the University of California Tobacco-Related Disease Research Program Grant and the California Agricultural Experiment Station.