In the early days of the pandemic, doctors noticed something about the people severely ill from COVID-19: Many were obese.

The link became more apparent as coronavirus swept across the globe and data mounted, and researchers are still trying to figure out why, NBCNews reported.

Excess weight increases the chances of developing a number of health problems, including heart disease and diabetes. And those are among the conditions that can make COVID-19 patients more likely to get very sick.

But there’s some evidence that obesity itself can increase the likelihood of serious complications from a coronavirus infection. One study of more than 5,200 infected people, including 35 percent who were obese, found that the chances of hospitalization rose for people with higher BMIs, even when taking into account other conditions that could put them at risk.

Scientists are still studying the factors that might be at play — the way obesity affects the immune system may be one — but say it’s another example of the pandemic illuminating existing public health challenges.

Obesity may be one reason some countries or communities have been hit hard by the virus, researchers say. In the United States, the obesity rate among adults has climbed for decades and is now at 42 percent. The rate is even higher among Black and Hispanic Americans.

A person who is 5 feet, 7 inches tall is considered obese starting at around 190 pounds, or a body mass index of 30. The increased risk for serious COVID-19 illness appears more pronounced with extreme obesity, or a BMI of 40 or higher.

Researchers say multiple factors likely make it harder for people who are obese to fight a coronavirus infection, which can damage the lungs. Carrying around a lot of extra weight strains the body, and that excess fat could limit the lungs’ ability to expand and breathe.

Another issue is chronic inflammation, which often comes with obesity. Inflammation is a natural way our bodies fight harmful intruders like viruses. But long-lasting inflammation isn’t healthy and could undermine your body’s defenses when a real threat arises.

“It’s like pouring gasoline on a smoldering fire,” said Dr. Dariush Mozaffarian, an obesity researcher and dean of Tufts University’s school of nutrition science and policy near Boston.

And even if people who are obese aren’t diagnosed with diabetes or heart disease, Mozaffarian notes their health may not be optimal.

How fat is distributed in the body may play a role too. One study found an increased risk for death from COVID-19 for people with severe obesity, but only among men. The findings could reflect that men tend to carry fat around the stomach, said Sara Tartof, a co-author of the study who researches infectious diseases at Kaiser Permanente in Southern California. That type of fat is more associated with the production of a hormone that could be contributing to more severe illness, she said.

Scientists are also exploring whether there’s something specific about the coronavirus itself that makes the obese more susceptible to getting very sick.

For example, the virus infects cells by attaching to receptors on the surface of certain cells. That receptor is abundant on fat cells and scientists are studying whether that makes them “a good nest for the virus,” said Dr. Francois Pattou at the University of Lille in France, who has co-authored research on the link between obesity and severe COVID-19 illness.

Complications in care can arise once hospitalized, too. To help with breathing, for example, doctors have been putting patients hospitalized with COVID-19 on their stomachs. But that can be difficult for the obese, making it more likely they’re put on ventilators.

“They need a machine to help just do the work,” said Dr. David Kass of Baltimore’s Johns Hopkins University, who has co-authored a study on obesity and severe COVID-19 illness.

Yet another concern: A COVID-19 vaccine may not be as effective for the obese, as seems to be the case with the flu and other vaccines.

Why that might be isn’t known, but one possibility is that obesity impairs an aspect of the immune system that needs to be activated for vaccines to work, said Dr. Nancie MacIver, who researches how weight affects the immune system at Duke University in Durham, North Carolina. And she said whatever factors are at play would likely be applicable to a COVID-19 vaccine, but added that it is still important to get it.

The Oxford University study, looking at more than 200,000 men, did not find an increased risk in people with higher overall body fat if it was spread around the body.

This suggests it is the specific location of the fat that makes males more prone to the killer disease.

Fat stored in the belly is considered the most dangerous type because it coats vital organs, such as the liver, pancreas and intestines.

This may interfere with their normal function and promote the growth of cancerous cells, the researchers said.

The latest research, presented at this year’s European and International Conference on Obesity (ECOICO), looked at 218,225 cancer-free men in the UK, whose medical data is stored in the UK Biobank.

Scientists monitored them for 10 years, looking at their body mass index (BMI), total body fat percentage, waist circumference, and waist-to-hip ratio.

Men in the top 25 per cent for waist circumference, they found, were 35 per cent more likely to die of prostate cancer than men in the bottom 25 per cent.

The largest group included those whose waists measured more than 40 inches (100cm). The waist does not include the hip bones but is the soft section between the pelvis and the ribs, level with the belly button.

Men in the smallest group were those who had waists smaller than 35 inches (90cm).

Meanwhile those in the top quarter for waist-to-hip ratio, another measurement of how much fat is located around the belly area, were 34 per cent more likely to die than men in the bottom quarter.

The risk remained the same even when medical history and lifestyle factors were factored in.

However, researchers did not discover any clear association between a man’s BMI or total fat percentage and prostate cancer.

This meant that even a man who was fatter or heavier overall may not be at the same level of increased risk if most of that fat was stored in their legs and arms.

It suggests those who specifically store most of their fat around their midriff were more prone to dying from the disease.

Dr Aurora Perez-Cornago, a nutritional epidemiologist at Oxford who led the study, said: ‘We found a significant association between concentration of body fat around the belly and waist and the risk of prostate cancer death, but no clear association between total body fat and risk of prostate cancer death.

‘However, a larger number of cases in this study together with studies in other populations are needed to confirm these findings.

‘A high BMI increases the risk of other diseases, including other types of cancer, so people should consider the implications of excess body fat wherever it is found in the body.’

Previous studies have indicated that ‘visceral fat’, which is stored in the belly, is the most dangerous type.

Excess visceral fat appears to boost numbers of a protein called fibroblast growth factor-2 (FGF2) which stimulates the growth of tumour cells. But research into visceral fat is still in its early stages.

Dr Perez-Cornago said: ‘This is the most dangerous fat because this fat is located around the vital organs.

‘It’s associated with metabolic and hormonal dysfunction and this is what may play a role in prostate cancer progression.’

She said the message to men was to exercise and eat a healthy diet to ensure they maintain a healthy weight and lower waist circumference.

Prostate cancer has become the most commonly diagnosed form of the disease in the UK.

A total of 57,192 men in England, Scotland, Northern Ireland and Wales were told they had it in 2018 – a substantial rise from 48,690 the previous year and up from around 24,000 in 1998.

It means diagnosis of prostate cancer has more than doubled in the past 20 years and it has now overtaken breast cancer as the most common form.

Experts attribute the increase to rising numbers of men getting tested as well as the growing and ageing population.

High-profile cases such as TV presenter Bill Turnbull and actor Stephen Fry going public with their prostate cancer have also shone a light on the once taboo subject.

A new study of more than 19,000 knee dislocation cases in the US between 2000 and 2012 provides a painful indication of how the nation’s obesity epidemic is changing the risk, severity and cost of a traumatic injury.

“Obesity greatly increases the complications and costs of care,” said lead author Dr. Joey Johnson, orthopedic trauma fellow at the Warren Alpert Medical School of Brown University and a physician at Rhode Island Hospital. “As the rate of obesity increases, the rate of knee dislocations increases. The total number of patients who are obese is increasing, so we are seeing more of these problems.”

Addressing obesity, said co-author Dr. Christopher Born, a professor of orthopaedics at Brown, could therefore help reverse the trends in the data reported in the Journal of Orthopaedic Trauma.

Obesity’s effects

Knee dislocations occur when the knee is badly disrupted because of multiple torn ligaments in the joint. Typically, this happens in vehicle crashes or contact sports like football. But Johnson and Born were inspired to look into the role of obesity because of what they’ve observed clinically over the last five years: an increase in knee dislocations among obese patients with an increased risk of vascular injury to the main artery that runs down the leg behind the knee.

Moreover, Johnson and Born have seen an increase in “low-energy” causes of dislocations, especially among obese patients. A few years ago, for example, Johnson saw a patient who experienced a knee dislocation after stepping off a ladder while hanging curtains.

To understand what’s going on more comprehensively, they analyzed records in the Nationwide Inpatient Sample, a database of patients who’ve had hospital stays. Over the study period, they found that obese or morbidly obese patients made up an increasing share of knee dislocation patients, rising to 19 percent of patients in 2012 compared to just 8 percent in 2000.

Vascular injury is a particularly severe complication because if undiscovered and untreated, it can lead to amputation of the leg. The team’s calculations from the data revealed that the odds of vascular injury during a knee dislocation were twice as high among obese or morbidly obese people than for normal-weight people.

Johnson said this finding is particularly insidious because a common clinical assumption is that vascular injury might be less likely among people suffering a low-energy knee dislocation. He and Born said the new research suggests physicians should be especially vigilant about vascular injury in obese knee dislocation patients, regardless of the cause.

“Orthopaedic and emergency medicine clinicians should have a heightened awareness for the potential of a knee dislocation in the obese patient following a low-energy fall,” Born said. “That subset of obese patients who come in with complaints of knee pain need to be carefully evaluated so as not to miss a potentially catastrophic vascular injury.”

The stakes, Johnson added, could be the leg itself.

“You don’t want to be fooled,” he said. “That patient could lose the leg, and their life could be changed forever.”

In addition to increased incidence and the likelihood of vascular injury, the researchers looked at the costs of care. Patients with vascular injury, which was twice as likely among obese patients, stayed in the hospital for an average of 15.3 days, while patients without vascular injury stayed for an average of 7.4 days. In keeping with that difference, average hospitalization costs were $131,478 for vascular injury cases and $60,241 for those who avoided vascular damage.

“This study shows the power of using large databases to glean meaningful clinical and economic information that can significantly impact health care costs,” Born said.

Though the data leave off in 2012, which is when Johnson began his residency, he said the trends are quite likely to have remained on track.

“Nothing would lead me to believe that the trend has been halted in any way,” he said.

Low levels of physical activity and inefficient sleep patterns intensify the effects of genetic risk factors for obesity, according to results of a large-scale study presented at the American Society of Human Genetics (ASHG) 2017 Annual Meeting in Orlando, Fla. These results confirm and strengthen previous findings based on self-reported activity.

Andrew Wood, PhD, postdoctoral researcher, who presented the work; Timothy Frayling, PhD, Professor; and their colleagues at the University of Exeter Medical School study the genetics of body mass index (BMI) and Type 2 Diabetes. In the past, Dr. Frayling explained, it has been difficult to measure interactions between genetic risk factors and aspects of environment and lifestyle in a systematic way.

“Until recently, physical activity and sleep patterns could not be measured with as much precision as genetic variants, and we relied on diaries or self-report, which can be very subjective,” Dr. Frayling said. In contrast, the new study made use of wrist accelerometer data, which is more objective and quantifiable, and a large genetic dataset from about 85,000 UK Biobank participants aged 40 to 70.

“We wanted to find out if obesity-related genes and activity level have an interactive effect on obesity risk — if there is a ‘double whammy’ effect of being both at genetic risk and physically inactive, beyond the additive effect of these factors,” said Dr. Wood. The researchers computed a genetic risk score for each participant based on 76 common variants known to be associated with elevated risk of obesity, and analyzed this score in the context of accelerometer data and participants’ BMIs.

They found the strongest evidence to date of a modest gene-activity interaction. For example, for a person of average height with 10 genetic variants associated with obesity, that genetic risk accounted for a 3.6 kilogram increase in weight among those who were less physically active but just 2.8 kilograms among those who were more active. Results were similar in analyses of sleep patterns; among participants with some genetic risk of obesity, those who woke up frequently or slept more restlessly had higher BMIs than those who slept more efficiently.

The researchers are currently examining whether this interaction between genetics and physical activity differs between men and women. They are also studying the effects of patterns of activity — for example, whether a consistent level of moderate activity has different effects from overall low levels punctuated by periods of vigorous activity.

“We hope these findings will inform clinicians who help people lose or maintain their weight, and contribute to the understanding that obesity is complex and its prevention may look different for different people,” said Dr. Frayling. “Ultimately, with further research, we may have the scope to personalize obesity interventions,” he said.