Loneliness is deadlier than obesity and should be considered a public health risk, experts have warned.

Those with bad social connections have a 50 percent increased risk of early death compared to those with good social connections, a review of studies on loneliness suggests.

Researchers in the US looked at 218 studies into the health effects of loneliness and social isolation.

They discovered that social isolation raised a person’s risk of death by half compared to obesity, which raised the risk of death by just 30 percent.

Dr. Julianne Holt-Lunstad, lead author and professor of psychology at Brigham Young University, said: “Being connected to others socially is widely considered a fundamental human need, crucial to both well-being and survival.

“Extreme examples show infants in custodial care who lack human contact fail to thrive and often die, and indeed, social isolation or solitary confinement has been used as a form of punishment.

“Yet an increasing portion of the US population now experiences isolation regularly.”

Feeling lonely is thought to make people feel worse mentally and physically — and those who are lonely tend to suffer worse symptoms when they are unwell than those who aren’t.

A recent survey by Granset, the over-50s social networking site, found that almost three-quarters of older people in the UK are lonely and most have never spoken to someone about how they feel.

It also discovered that about 70 percent said their close friends and family would be surprised if they said they were lonely.

Recent Office of National Statistic stats show Britain is the loneliest country in Europe.

And, according to the Campaign to End Loneliness, the UK’s loneliness epidemic costs business $26 million per year for the costs associated with health outcomes and sick days.

Holt-Lunstad added: “There is robust evidence that social isolation and loneliness significantly increase risk for premature mortality, and the magnitude of the risk exceeds that of many leading health indicators.

“With an increasing aging population, the effect on public health is only anticipated to increase.

“Indeed, many nations around the world now suggest we are facing a ‘loneliness epidemic.’

“The challenge we face now is what can be done about it.”

She suggested greater priority be placed on research and resources to tackle loneliness such as social skills for children in schools.

Previous research has suggested that solitary adults reported much more severe symptoms when they were unwell.

A study by Rice University in Texas found that, while they were no more likely to catch a cold, lonely adults felt far worse when they did.

Experts said GPs should factor in a patient’s social circumstances when treating them.