Extremely severe obesity is on the rise in kids—along with a barrage of health problems

Obesity rates in children have been on the rise for decades, having quadrupled from 1990 to 2022, and along with the rise in obesity, comes a rise in health risks. However, obesity can be broken down further into categories based on severity.

In children, obesity is defined as having a body mass index (BMI) above 95% of kids of a similar age and sex. This differs from the way adult obesity is defined, which uses a simple BMI number of 30 or higher. Currently, childhood obesity is separated into three categories defined by BMI, with class 1 at or above the 95th percentile, class 2 at 120% to 140% and class 3 (severe obesity) at 140% or higher of the 95th percentile.

A new study by researcher published in the JAMA Network Open, suggests breaking up these categories even further by adding a class 4 and 5, defined as a BMI from 160% to 180% of 95th percentile and a BMI over 180% of 95th percentile, respectively. This further refinement seeks to differentiate the health risks involved with these "extremely severe" categories of obesity.

The study highlights how the health risks of children at these levels of obesity become increasingly dangerous when compared to children in lower obesity classes or to children with healthy weights.

The researchers found a startling increase of 253% in the prevalence of extremely severe obesity in children from 2008 to 2023. In addition, all other categories of obesity increased over this time period, although at lower rates. They found the increase was particularly dramatic in adolescents from the ages of 16 to 18 and in non-Hispanic black children.

The analysis of health complications in these children revealed an increased risk of multiple diseases with increasing classes of obesity. In particular, diabetes, prediabetes, metabolic disease—which is associated with increased risk of heart disease and stroke—and liver diseases were common.

Insulin resistance, a precursor to many of these health problems, was found in 100% of the class 4 and 5 participants, compared to 81% in classes 1–3 and 27% in those without obesity. Across the board, all diseases were more prevalent in higher classes of obesity than in lower classes and the lower classes of obesity were associated with increased risk compared to healthy BMI risks.

The study authors point to the need for action on this increasingly severe problem.

Eliane Münte et al, Prevalence of Extremely Severe Obesity and Metabolic Dysfunction Among US Children and Adolescents, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.21170

Scientists discover genetic condition that causes paralysis following mild infections

Doctors and genetic researchers  have discovered that changes in a gene leads to severe nerve damage in children leading to paralysis following a mild bout of infection.

The paper, "Acute-onset axonal neuropathy following infection in children with biallelic RCC1 variants: a case series," is published in The Lancet Neurology.

Researchers have now discovered that changes in a gene called RCC1 led to this severe nerve damage. In over half of the children, doctors suspected the diagnosis of a different severe nerve condition that can develop after infection called Guillain Barré syndrome.

The researchers performed laboratory studies on skin cells taken from patients and in specially genetically engineered fruit flies to show that the damage to nerves can be caused by certain chemicals.

Skin cells from patients when looked at under special microscopes have changes very similar to those seen in the cells of patients with motor neuron disease where muscles, including those controlling breathing and swallowing, become weak.

As children are well before they develop nerve damage following an infection, this gives us an opportunity to treat at risk children before problems occur.

J Robert Harkness et al, Acute-onset axonal neuropathy following infection in children with biallelic RCC1 variants: a case series, The Lancet Neurology (2025). DOI: 10.1016/S1474-4422(25)00198-X

New research says it is okay to eat eggs 

Researchers clear eggs of heart disease blame

From poached to panfried, when it comes to eggs, it's all sunny side up, as new research  confirms that this breakfast favorite won't crack your cholesterol.

Long blamed for high cholesterol, eggs have been beaten up for their assumed role in cardiovascular disease (CVD). Now,  researchers have shown definitively that it's not dietary cholesterol in eggs but the saturated fat in our diets that's the real heart health concern.

In a world-first study published in The American Journal of Clinical Nutrition, researchers examined the independent effects of dietary cholesterol and saturated fat on LDL cholesterol (the "bad" kind), finding that eating two eggs a day—as part of a high cholesterol but low saturated fat diet—can actually reduce LDL levels and lower the risk of heart disease.

CVD is the leading cause of death worldwide, responsible for nearly 18 million deaths each year.

Eggs have long been unfairly cracked by outdated dietary advice, the researchers  say, 

They're unique—high in cholesterol, yes, but low in saturated fat. Yet it's their cholesterol level that has often caused people to question their place in a healthy diet.

In this study, the researchers separated the effects of cholesterol and saturated fat, finding that high dietary cholesterol from eggs, when eaten as part of a low saturated fat diet, does not raise bad cholesterol levels.

Instead, it was the saturated fat that was the real driver of cholesterol elevation.

Sharayah Carter et al, Impact of dietary cholesterol from eggs and saturated fat on LDL cholesterol levels: a randomized cross-over study, The American Journal of Clinical Nutrition (2025). DOI: 10.1016/j.ajcnut.2025.05.001