The British Fertility Society (BFS) is recommending that women who are severely overweight women should not be given access to free fertility treatment.
In a new report the experts also say that obese women should be referred to a dietician and given exercise advice before they are offered IVF treatment and their treatment deferred until they "demonstrate response to these interventions".
Those who are severely obese (BMI over 36) would have to show weight loss before they were approved.
The report also recommends that single women and same sex couples should be offered the same access to IVF treatment as heterosexual couples and no women over the age of 40 should be allowed to start NHS-funded fertility treatment.
The recommendations by the BFS which suggest women with a body mass index of 36 or more should be denied IVF treatment on the NHS, are even more direct than current NHS guidelines which although they say overweight women should be advised of the health risks, but do not deny the treatment.
According to the BFS, as obese women are less likely to get pregnant and more likely to encounter health problems, it is common sense to tackle the problem before trying to access fertility treatment.
They advise that women with a body mass index of 29 or more undergo a programme of diet and exercise before being allowed IVF treatment.
The BFS also recommends that smoking should not be a reason for exclusion but patients who smoke should be given advice about its implications, and waiting times for treatment should be the same as for any other medical condition.
The BFS says it is aiming to tackle the 'wide disparity' in the social criteria used by individual NHS trusts in deciding whether treatment should be allowed.