Esau's Birthright

This passage is often used to condemn Esau for thinking so little of his birthright that he would give it away for some food. But he also says that he is about to die, so if that happens his birthright won't be valuable to him anyway and he'd rather live. I wonder how close he was to actually dying, vs just being really hungry and feeling like he might die. Because if he was on death's doorstep you'd think Jacob would be blamed more for taking advantage of his brother.