Mike Cresswell, AQA's director general, presented figures suggesting that take-up could be as low as 100 students a year for the languages diploma.
Speaking at AQA's annual A-level awards conference, he explained that his analysis was based on A-level take-up.
With the advanced diploma meant to be equivalent to three A-levels, he said, a science diploma would be akin to a student taking A-levels in three science subjects - maths, physics, chemistry or biology. According to data from all the exam boards, some 22,424 did so this summer.
In a similar analysis of the humanities diploma, he found that 3,751 took three humanities A-levels this summer. However, only 97 took three languages.
Dr Cresswell then said that, even if one was more generous and said that the new diplomas would be the equivalent of taking only two A-levels in a subject area and having free choice of third, demand might still not be great.
He said: "Although the three new subject-based diplomas will provide a viable choice for a few students at advanced level, especially in science, it is hard to conclude ... that there will be great demand for them from young people."
A Department for Children, Families and Schools spokesman said: "Such speculation fails to acknowledge that we are living in a fast-changing world.
"Diplomas are designed to be the qualification of the future, to equip young people with the skills they will need to prosper in the 21st century. So to use today's figures for a different qualification and suggest take-up will be low fails to prove any point."
Dr Cresswell said he was not arguing against the introduction of the new diplomas, but that they would not, by themselves, meet the demands of most young people.
Instead, he encouraged the Government to introduce another new diploma - the 18th - which would give students the chance to combine any subjects of their choice.
He then presented information on AQA's own new qualification, the AQA Bacc, plans for which were revealed in The TES last year.
The wrap-around qualification will be awarded to pupils gaining three A-levels, an AS in an unrelated subject, an extended project and enrichment activities, such as community service.
Dr Cresswell suggested ministers should consider a similar model for advanced diplomas.
The three new advanced diplomas were announced last month to supplement the existing 14 work-related ones, which will be launched next year. The advanced diplomas are the first to be offered in academic subjects and are widely seen as offering more prestige to the diploma programme.
Ed Balls, the schools secretary, this week announced a new group, The Diploma Employers Champions Network to promote the diplomas. It will include representatives from 18 firms and be led by Sir Alan Jones, of Toyota UK.
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Curriculum innovation, page 16.