According to Just Retirement, people are far likely to be obese around the age of retirement than at any other time in their lives, which could have a direct effect on those shopping around for an annuity.

Government figures released towards the end of December show nearly a third of people at retirement age are obese yet still only 20% of all annuities sold are enhanced for health or lifestyle reasons.

Dr Tim Crayford, chief medical advisor at Just Retirement, said: “That suggests there are a lot of people who are not shopping around and therefore missing out on extra income for the rest of their lives.”

People are considered obese if their body mass index (BMI), a figure calculated using weight and height, exceeds 30 kg/m2.

For example, a man weighing 90kg and 173cm tall (14st 2lb and 5ft 8ins) has a BMI of just over 30 kg/m2.

A woman weighing 77kg and 160cm tall (12st 1lb and 5ft 3ins) would also be just over 30 kg/m2.

People approaching retirement are encouraged to disclose factors such as their weight and other health issues, and if their partner has a history of poor health, because it may help them secure a higher income with their pension funds.

Crayford continued: “Someone who is overweight or obese is more likely to suffer from other health problems.

“Weight has a bearing on life expectancy so it is one of the factors that we take into account when calculating whether we can offer a higher income than a standard annuity.

“For a retiree in otherwise good health, it may help them qualify for an enhanced annuity. Or if there are ongoing health issues, weight may be a complicating factor that lifts the income further.”

Just retirement says that other common conditions can affect whether you might qualify for a larger annuity.

Official figures show, for example, that 44% of those in the 55-64 age group might be at risk from problems due to high blood pressure and this rises to nearly 59% for those aged 65-74.

Crayford added: “Anyone thinking of taking their pension should expect to be asked about their general health and lifestyle and about any treatment they are receiving.

“People can be embarrassed about talking about their weight but if they’re shopping for an annuity, they need to be totally honest.”