Just one in 141 obese people in the region currently have access to NHS weight-loss medication.
This is more than double the national average of one in 345.
The data from Oviva, the NHS’s largest weight-loss treatment provider, highlights a two-tier healthcare system where access depends on where someone lives or their ability to pay privately.
The research reveals only 23 per cent of people in the South West are aware that weight-loss medications are available through the NHS and understand the eligibility criteria.
Nearly half believe only those who can afford private healthcare have access to the most effective weight-loss treatments.
Martin Fidock, managing director at Oviva, said: “The postcode lottery exposed by our data is leaving thousands behind.
“We urgently need national action to ensure everyone who meets the criteria can get the support they need, no matter their postcode or bank balance.”
At least 11 of the 42 NHS integrated care boards have restrictive criteria.
National guidance states patients with a BMI of at least 35, or 30 with a related condition, should be able to access these drugs.
However, restrictions are being imposed at random to cut costs.