Portsmouth residents are set to have the second-worst life expectancy in the south of England.
The figures show that in 2030, Portsmouth men are expected to live to the age of 84.6 and women 87.6.
Neighbouring Havant, Gosport and Fareham – and the rest of the county – will live for longer.
Only Thanet in Kent, which includes Margate, has shorter expected lifespans. Men there are expected to live until the age of 84.2 and women would live on average to 86.6.
Nationally, the average woman will live to 87.6 and man to 85.7.
Kate Lees, a consultant in public health for Portsmouth City Council, said: ‘Reducing the burden of ill-health and increasing healthy life expectancy are key aims for public health in Portsmouth.
‘Unhealthy lifestyle behaviours such as smoking, poor diet, lack of physical activity and high alcohol consumption put individuals at risk of poor health and conditions such as diabetes, heart and kidney disease, stroke and cancer that add to the causes of premature death.
‘To improve health in the city the council works with family doctors, the NHS, and the social care user group Healthwatch, to form the health and wellbeing board and set a joint health and wellbeing strategy.
‘This strategy focuses on five priority areas – getting the best start in life, promoting prevention, supporting independence, intervening earlier and reducing inequality.
‘We all need to take control to make the best choices for our health and wellbeing – stopping smoking, drinking less, eating well and moving more can make significant improvements to our life expectancy.’
The three-and-a-half year study was headed by Professor Majid Ezzati, a specialist in public health.
He said: ‘We used a number of methods to project the 2030 outcomes, and we believe they are fairly accurate.
‘To test it, we used the same methods to look at previous outcomes to predict current life expectancy, as this gives us a marker to see how accurate it is.
‘On average, this was correct and so we have used this to project the outcomes for 2030.
‘What we saw with Portsmouth is a continued slowing down of life expectancy increasing, compared to other areas.’
The report by Imperial College in London says at the moment men are expected to live until 79 in Portsmouth, and women 84.
In Havant people are currently expected to live until 83, in Fareham the average is 83.8, and in Gosport it is 81.7.