He who occupies himself in Torah, it is not possible that his neck should be thick and his body should be fat (Mivchar Peninim 1:29).
On the face of it, this is a perplexing statement. What about the famous Talmudic sages who were very heavy? R. Elazar b'Rebbi Shimon and R. Yishmael b'Rebbi Yosi were very fat. R. Yochanan's and Rav Papa's were also big (but not as big( Bava Metsiah 84a). In fact, in our own day,we had Rav Simon Schwab and Rav Shlomo Freifeld who cut an imposing figure.
A commentary to Mivchar Peninim attempts to explain this by quoting a Tosafos in Taanis 7a that had the sages been more ugly, they would have been even greater. Similarly, those sages who are fat despite their fasting, would have been much heavier, had they not fasted.
This reminded me of an interesting story quoted in the biography of Rabbi Freifeld byR. Yisroel Besser. He reports that Rav Shlomo was eating schnitzel Pentecost in the when a famous biographer of Jewish figures passed by. Rabbi Freifeld humorously exclaimed: "Oy, now they will not write a biography about me. So, is it Shlomo's fault that Shlomo likes schnitzel?"
It seems to me that the mindset that scholars must be thin and pale, is no longer the prevailing one in Judaism, at least, not since the Chassidic revolation. There was a time when there operative mindset was that the weakening over the body to the strengthening of the soul. Since Avodah B'Gashmiyus" (Serving G-d through the body) displaced the idea of ascetism and weakening the body, the previous paradigm of self-denial no longer operates. That does not mean that one should not limit oneself for reasons of health or to be in balance and practice self control. However, it is no longer a virue in itself but merely a stepping stone to other achievements.
Perhaps the Talmudic sages in Bava Metziah were harbingers of the Chassidic revolution?