There has been no change in the disparity of life expectancy between the richest and poorest residents in South Hams, new figures show.
However, across England, the gap between the life expectancies of the richest and poorest people has grown since 2010-12.
A leading health professional has written to dozens of MPs in the worst-affected areas, including former Prime Minister Liz Truss, Levelling Up Secretary Michael Gove and former Health Secretary Steve Barclay.
Professor Sir Michael Marmot told dozens of MPs their constituents are "suffering avoidable ill-health and living shorter lives than they should".
New analysis by academics from the Institute of Health Equity at University College London shows the difference in life expectancy of the least and most deprived residents in South Hams has broadly not changed.
In 2017-19, before the coronavirus pandemic, the wealthiest male residents were expected to live 3.6 years longer than their poorer neighbours.
This fell to 2.1 for female residents, though both figures were broadly in line with 2010-12.
Sir Michael has written letters to the 58 MPs whose constituencies lie wholly or partially in the worst-affected local areas.
Also among the recipients are Culture Secretary Lucy Frazer, Conservative Party chairman Richard Holden, justice minister Edward Argar, former immigration minister Robert Jenrick, and former health minister Maggie Throup.
"We need you to fight for all your constituents’ health. They are suffering avoidable ill-health and living shorter lives than they should due to poor policies and cuts to essential services," Sir Michael wrote.
He has also written to the leaders of all major political parties demanding action.
In his letter to Prime Minister Rishi Sunak, Sir Michael said austerity and funding cuts have "harmed health and worsened health inequalities".
The analysis also shows South Hams District Council's spending power declined by 32% in real terms from 2010-11 and 2020-21, when factoring in council tax rises and central government funding.
A government spokesperson said: "As set out in our Levelling Up White Paper, we are committed to narrowing the gap in healthy life expectancy by 2030 and to increasing healthy life expectancy by five years by 2035.
"Our upcoming Major Conditions Strategy will help us do this, by tackling the key drivers of ill-health in England.
"We are also investing £15 billion in local communities across the UK as part of our long-term plan to level up, ensure opportunity is spread more equally and to reduce inequalities."
They said they have given councils in England up to £64.7 billion for 2024-25, a 7.5% rise in cash terms.