Researchers say being ‘fat but fit’ could be less deadly than being underweight

A major new study found that carrying a few extra pounds might not be as dangerous as being underweight, especially for those who are “fat but fit.”

Researchers from Aarhus University Hospital in Denmark followed more than 85,000 adults and found that people who were underweight were nearly three times more likely to die during the study period than those at the high end of the normal body mass index (BMI) range. 

Even participants within the “healthy” range, but on the lower side, faced a higher risk of early death.

FOR THE FIRST TIME, THERE ARE MORE CHILDREN IN THE WORLD WHO ARE OBESE THAN UNDERWEIGHT

Meanwhile, those who were overweight or moderately obese did not face higher death rates compared to people with BMIs in the upper-normal range.

The findings challenge long-standing assumptions about BMI — a calculation using weight and height — and health, suggesting it may be possible to be “fat but fit” and that carrying a few extra pounds may not be as harmful as once thought, according to a press release. 

The researchers presented their findings at the annual meeting of the European Association for the Study of Diabetes (EASD) in Vienna last week.

BODY FAT PREDICTS MAJOR HEALTH RISK THAT BMI MISSES, RESEARCHERS SAY

The greatest risk, however, came at both extremes: severe obesity and being underweight.

“Both underweight and obesity are major global health challenges,” said lead researcher Dr. Sigrid Bjerge Gribsholt, of Aarhus University Hospital.

Obesity can disrupt the body’s metabolism, weaken the immune system and lead to diseases like Type 2 diabetes, cardiovascular diseases and up to 15 different cancers, while being underweight is tied to malnutrition, weakened immunity and nutrient deficiencies, Gribsholt warned.

According to the researchers, body fat distribution and underlying health conditions play a big role in overall health.

CANCER DEATHS HIT ‘ALARMING’ SURGE DUE TO COMMON HEALTH CONDITION, EXPERTS SAY

“Visceral fat — fat that is very metabolically active and stored deep within the abdomen, wrapped around the organs — secretes compounds that adversely affect metabolic health,” said Professor Jens Meldgaard Bruun, another of the study’s researchers.

“As a result, an individual who has a BMI of 35 and is apple-shaped — the excess fat is around their abdomen — may have type 2 diabetes or high blood pressure, while another individual with the same BMI may [be] free of these problems because the excess fat is on their hips, buttocks and thighs,” he added.

The treatment of obesity should be personalized to take these factors and other conditions into account when setting a target weight, Bruun said.

MORE IN HEALTH NEWS

Fox News Digital has reached out to the study’s authors for comment. 

Dr. Akshaya Srikanth Bhagavathula, an epidemiologist at North Dakota State University who was not involved in the research, told Fox News Digital the findings support other recent research but challenge current medical guidelines that assume health risks rise steadily with BMI.

“The higher death rates in people with lower BMI likely occur because hidden illnesses cause the situation to appear backwards,” Bhagavathula told Fox News Digital. “Diseases like cancer or heart failure cause weight loss first, which makes low weight seem more dangerous than it actually is.” 

CLICK HERE TO SIGN UP FOR OUR HEALTH NEWSLETTER

Obesity, meanwhile, tends to come before serious health problems, according to the World Health Organization.

Bhagavathula added that in older adults, age-related muscle loss increases vulnerability, such as to falls and infections, while mild excess weight may provide a “protective effect” by offering energy reserves during illness. Denmark’s healthy and active lifestyle, including widespread cycling, may also contribute to that effect.

He emphasized that BMI should be considered alongside other measures like waist-to-height ratios, muscle mass, cholesterol and blood sugar levels, sex and ethnicity.

“Current health messaging often focuses too heavily on weight loss, creating shame and unnecessary medical treatment for people who are overweight but have normal body function,” he continued. “These findings suggest shifting toward a nutrition approach that focuses on how the body processes food, emphasizing physical activity, balanced eating, and blood tests … rather than BMI alone.”