Explanation: As long as we can pursue experts, we do. We rely on the Choleh himself only when there are not experts at all;

All the more so, when an expert doctor says that he need not eat, and the Choleh says that he must eat, we do not rely on him to contradict the expert.

Explanation: Rabanan argue about whether or not the Halachah follows Mar bar Rav Ashi.

Opinion #1 (Seder Tana'im v'Amora'im): The Halachah follows Mar bar Rav Ashi in the entire Gemara, except for Meifach Shevu'ah (reversing an oath) and Odisa (the Kinyan of admission);

Meifach Shevu'ah is in Shevu'os 41a. Odisa is in Sanhedrin 29b.

Opinion #2 (R. Chananel): The Halachah follows him in the entire Gemara, except for Meifach Shevu'ah and clear or white (either of these shows that an area is the juncture of the sinews - Chulin 76b). The Siman to remember this is "Hafach Lavan";

Opinion #3 (Rav Hai Gaon and R. Gershom): The Halachah follows him only regarding Meifach Shevu'ah and Odisa, but everywhere else, not.