NOW! 126 lbs.
THEN 293 lbs.
HER WEEKDAY ROUTINE
5:00 A.M. | ON THE MOVE
After she has a hard-boiled egg to "boost her metabolism," Muniz hits her home gym, first riding a stationary bike for an hour, then working out to Denise Austin's Fit & Lite show on Lifetime.
12:00 P.M. | LUNCH BREAK
The key to avoiding the lure of unhealthy snacks? "I have a different fruit at every meal," says Muniz (with students). "You've got to keep your body intrigued. You can't eat the same thing every day."
10:00 A.M. | CLASS ACTION
Stretching with students before a dress rehearsal of The Importance of Being Earnest, Muniz says, "There's no way I could have done that before." At nearly 300 lbs., "I used to just stand still and direct."
6:00 P.M. | GOOD MEASURE
Muniz whips up baked chicken with steamed squash and zucchini in just 30 minutes. The most important tool in her kitchen: a food scale. "I even take it to restaurants to weigh my meat entree," she says.
9:00 A.M. | WEIGHING IN
Muniz meets each Saturday with Michelle Urdialez, a counselor at the LA Weight Loss Center where a pair of Muniz's old size-24 jeans hangs on the wall to inspire others. The check-ins, she says, keep her "on track."
10:30 A.M. | SPOUSAL SUPPORT
"We spend more time outdoors now," says Muniz (hiking in a state park with husband Rey, who has lost 40 lbs. since Mandy changed her own habits). "Before I didn't even have the energy to watch TV with him."
For more pictures, go to PEOPLE.COM/HALFTHEIRSIZE