  We explore alternate theories of gravity where the gravitational term in the
Lagrangian $\frac{R}{8\pi G}$ is replaced by a function $f_1(R)$ and the matter
Lagrangian is multiplied by a function $f_2(R)$. We argue that nuclear physics
can provide strong experimental constraints on such theories. In particular
using energy conditions on the pressure in the $^4$He nucleus, for
$f_1(R)=\frac{R}{8\pi G}$ and $f_2(R)=1+\lambda R$, we find a limit of
$|\lambda| < 5\times 10^{-12}\, \hbox{m}^2$, more than thirty orders of
magnitude stronger than the previous limit.
