Al Roker had bypass surgery and I thought the Keto diet was the reason he lost weight.

(weight loss surgery and maybe keto diet helped him lose weight. You can't just pick of those things because BOTH took place)

Al Roker Diet

The Al Roker Diet is described in this TV personality’s new book, Never Going Back.
Al Roker has been a long time host of NBC’s The Today Show and weighed close to 350 pounds a decade ago.

He had gastric bypass surgery and lost 190 pounds, however, the pounds started to creep back on due to the sickness of his father.

https://www.freedieting.com/al-roker-diet