In 1984, when Winston said to Julia, "You're only a rebel from the waist downwards," what did he mean?

rebels
against the physical privations that come with being an outer Party member. Inner Party members
enjoy all sorts of privileges denied to the rank and file, such as good coffee, wine and nice
apartments. Julia rebels against the puritanical hypocrisy of the system by having sex with men
who can offer her the comforts she wants, including sex, but also consumer goods, such as make
up. Unlike , she is not concerned with the nature of truth or the nature of reality. She doesn't
really care if the Party says two plus two equals five or whether or not the Party invented the
airplane. She simply wants to have some pleasure in her life (and part of this includes the
sense of victory that comes with beating the system) so that she can experience something beyond
an endless round of toil, cheap gin, and rage. 

While Winston's statement
sounds like a put down, in fact, he admires her pragmatism, and it is important to remember that
without her know-how, she and Winston would never have gotten together. She approaches him and
arranges the first meeting. She gets them luxuries like real coffee. 

In the
end, she and Winston fall in love, and she embraces his idea of joining the Brotherhood and
rebelling in a more overtly political way against the Party.