According to figures from NHS Digital there were 3,150 people admitted with a primary or secondary diagnosis of obesity in the city in 2019, up from 2,775 in 2018.
This means 1,662 out of every 100,000 people in Portsmouth needed medical attention due to being clinically overweight - more than the south east average of 1,382.
And in Portsmouth 65 people underwent bariatric surgery in 2019 - or 33 out of 100,000 people, which is significantly more than the England average of 12 per 100,000.
This was an increase compared to 55 in 2018.
Public health boss for Portsmouth, Helen Atkinson said the rates could be linked to areas of deprivation.
She said: ‘Portsmouth has high levels of deprivation when compared to other areas within Hampshire and we know deprivation is a key factor in obesity rates. There are greater levels of health inequality in more deprived communities, including higher rates of obesity, which have a direct impact on levels of ill-health, long term conditions and levels of disability.
‘Prevention of obesity needs a whole city approach, focusing on the two main drivers of obesity - physical activity and healthy diet.
‘We'll be focusing on our most inactive groups - women and girls, black, Asian and minority ethnic communities, those with disability and long-term conditions and other highlighted groups.
‘It is especially important for children to stay a healthy weight, as we know that children who are overweight or obese are much more likely to be overweight as adults.
‘Our new regional physical activity strategy will launch this summer and will be used by the Active Portsmouth Alliance and a range of partners.’
When asked about the impact the Covid lockdown could have on obesity levels, Ms Atkinson said it would be ‘difficult to predict.’
‘It's important to look at longer-term trends rather than just yearly changes, however we'll monitor the data and continue to work with partners, both locally and nationally, to tailor support as needed,’ she said.
‘Initially, we'll do this using our allocation of Public Health England's funding to increase weight management provision until March 2022. It's been well documented that obesity poses a significant risk of poorer Covid outcomes and it's hoped this money will help kick-start weight-loss journeys for a proportion of our residents who are currently obese, to protect their health now and in the future.’
The data also showed women and girls were more likely to be obese with 2,090 of them having a diagnosis of obesity in 2019, compared to 1,065 men and boys.
Across England 1,869 per 100,000 people were admitted to hospitals with a diagnosis of obesity.
In Hampshire this was 1,387 per 100,000 people.
As previously reported, figures from Public Health England showed 66 per cent of adults in Portsmouth were classed as overweight or obese in 2018.