Uniform scale convert to 1,1,1

Hey ya I’m ne here and I in Blender and want to export a test mesh to UDK for testing. My problem is that I become an error that my mesh has to have the uniform scale of 1,1,1 but I have aboit 0.3,2.5,1.0.
But how can I convert my mesh to 1,1,1 without deforming it ??

Because when I click Alt + S it scales it to 1,1,1 but my mesh deforms ( it’s a clear behaviour ) but what can I do to fix that ?

Apply it. Ctrl+A -> scale.