I am using the follwing equation:

1/1-P=a0+a1.x+a2.y+a3.z+a4.x.y+a5.x.z+…

The results indicate that significative parameters are a2, a3, a4 and a7.

Now, a7 is a quadratic term; that parameter is food intake.

My question is: How do I interpret biologically that food intake^2 is significant but not significant when it's not quadratic?How do I explain that?

Thanks very much.