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Tuesday 5 December 2023 Dublin: 5°C
shedding the pounds

Your immune system might be making you fat, major new Irish research suggests

“It is too simplistic to say eat less, move more and the weight will come off,” said lead researcher Professor Donal O’Shea.

NEW RESEARCH INVOLVING has shown that the immune system could be responsible for as much as 40% of our body’s ability to regulate weight.

Irish men have the highest Body Mass Index (BMI) in Europe, while Ireland also has the second-highest levels of obesity among women (37%) – just one percentage shy of table-toppers Britain.

Research by a team of Irish, US and Canadian scientists suggests that your immune system matters much more than previously thought.

Brendan Quinn is a fitness instructor who became obese after he developed an immune system disorder. With no change in his diet and exercise levels, his weight went from 76kg to 120 kg over a three-to-four year period.

“I was really struggling to try to lose the weight,” he said, despite being strict with diet and exercise.

Professor Donal O’Shea, consultant endocrinologist at St Vincent’s Hospital and the Conway Institute at UCD, and one of the lead authors on the research paper, approached Quinn offering an immune-system approach.

“I was very happy to try this new approach which tried to get my immune system to work better in order to then allow my body to lose weight,” Quinn added.

The results were almost immediate. I lost 12 kg in the first five weeks, and a total of 23 kg since I started treatment five months ago.

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Swiss army knife

The team discovered a common immune cell called the invariant natural killer T cell (iNKT cell), played a key role in weight loss.

The iNKT cell is described as the Swiss army knife of the immune system because it does so many jobs. It helps fat cells make a protein (FGF-21) that metablosises, or turns white fat into a much healthier brown fat.

“This browning of white fat uses large amounts of energy, leading to increased metabolic rate and weight loss,” said TCD professor Dr Lydia Lynch, who is also an assistant professor at Harvard Medical School.

We know that people who are obese often have sluggish immune systems and a lower amount of these iNKT cells.

“With less iNKT cells, the body doesn’t make FGF-21, and this prevents the body from converting white fat to change it into brown fat.

“So, if you stimulate the body to produce iNKT cells, you can increase the amount of FGF-21. This, in turn, leads to enhanced browning of white fat, and increased metabolic rate and weight loss.”

The researchers said this new knowledge opens up new areas for treating weight loss.

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“These findings represent a significant step forward in our understanding of why people often find it so hard to lose weight, despite their best efforts,” Professor O’Shea said.

The findings should help break many of the stigmas associated with obesity, and most importantly, they could dramatically improve outcomes for patients.

He said the research underlies the absolute importance of preventing weight gain happening in the first place.

“We know that once weight is gained, for the majority of people, it is very difficult to lose that weight,” Professor O’Shea said. “It is too simplistic to say eat less, move more and the weight will come off.

It doesn’t actually work like that. The body has a very powerful reaction to defend against weight loss, which we now know involves the immune system.

“We normally think of the immune system as something that guards against infection and diseases.

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Threat to survival

“However in evolutionary terms, a sudden or rapid weight loss could be a more immediate threat to survival,” O’Shea added.

This immune system response contributes to why people really struggle to lose weight, despite their best efforts to control calories and do exercise.

“Our findings give us a much better understanding of why this is so and they illustrate the dynamic role that the immune system plays in regulating body weight.”

Graham Love, Chief Executive of the Health Research Board, who funded the Irish arm of the research, said: “This is a highly significant breakthrough in understanding obesity, one of the global health challenges of our time.

“It will help change approaches we take to care and transform many people’s lives.”

The research was published today in the journal Cell Metabolism.

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