Agree with both about 饿. yes 馁 is ancient Chinese words when refer to be hungry. But 馁 has another meaning while putting together with 气. "气馁" means to lost confidence and courage to do something again，it's pretty common phrase. e.g. 人生遇到困难是平常事,一定不要气馁.

饿 is a feeling means hungry, such as sentence"我饿了" means “I'm hungry.” 馁 is a uncommon word ,even a native speaker may have no idea about it,you can search it on a dictionary if you really want to know what is means.If you are a begginer，it doesn't matter if you don't know it.

馁 is an ancient Chinese language, also known as Literary Chinese, which is a traditional style of written Chinese that evolved from the classical language, making it different from any modern spoken form of Chinese. The two characters mean the same thing except for only one difference here: 馁：Ancient literary Chinese 饿：Modern spoken Chinese

饿 is a feeling means hungry, such as sentence"我饿了" means “I'm hungry.” 馁 is a uncommon word ,even a native speaker may have no idea about it,you can search it on a dictionary if you really want to know what is means.If you are a begginer，it doesn't matter if you don't know it.