The hire comes as the organisation attempts to step up its profile and drive membership among dieticians and nutritionists.
Rimmer said the trade body wanted to become the voice of the industry.
She will try to position it as an expert on dietary issues and raise awareness of the help dieticians can offer patients suffering from a range of problems, particularly obesity.
The BDA is also persuading employers to make more effort to tackle obesity in the workplace.
It wants companies to encourage staff to be more active, for example by making shower facilities available so that people can walk or cycle to work.