Jessica Biel's trainer, Jason Walsh [1] has recently revealed to People [2] what this starlet has been doing for the past 8 months to be looking so darn buff.

Jessica Biel’s Workout:

• Stretch: One of her favorite warm-ups is the walking lunge. “This stretches the larger leg and glute muscles,” says Walsh. How-to: With feet together, lunge first with right leg. Bring left foot alongside right. Lunge with left. Do 8-10 per leg.
• Cardio: “It’s the cardio that leans her out,” says Walsh. After a ½-mile jog, they hit the track for two 200-meter, 150-meter and 100-meter sprints.
• Core: “Hanging leg raises don’t build a six-pack, but they flatten,” says Walsh. “Jessica hates them, but she powers through!” How-to: Hanging from a high bar or rings, pull knees up slightly above waist. Do three sets of 15 repetitions.
• Plyometrics: “These hurt,” says Walsh of stair jumping. “Even athletes hate them. After Jessica did these the first time, she would’ve punched me if she had the energy.” How-to: Jump from the bottom step of a flight of at least 20 stairs to the third. Keep going, skipping a stair each jump.
• Weight Training: “We tend to use lighter weights and do more reps,” he says. “We keep moving, so it becomes a cardio workout too.”
• For the waist: They do the Russian Twist. Sit down and lean back slightly. Hold a 5-lb. medicine ball and twist from side to side, 15 twists per side, three reps.
• For shoulders/biceps: Stand with knees slightly bent. Hold 10-lb. weights in each hand. Curl to chest. Rotate hands, palms face outward. Press overhead together. Do 3 sets of 10-12 reps.

Want to find out about Jessica's diet and new year's resolution too, then .

Jessica Biel’s Diet:

• “Clean foods”— those that aren’t processed—are on the menu Walsh created. “She eats complex carbs at the beginning of the day,” he says, “and tapers off by the end.”
• Breakfast: 1 cup of oatmeal with handful of berries.
• Snack: 1 slice whole wheat toast, 1-1 ½ tbsp. of almond butter and sliced bananas on top.
• Lunch: Salad with 5-6 oz of chicken, vinaigrette dressing.
• Snack: A banana, apple or strawberries.
• Dinner: 6oz. of fish, plate full of veggies, 1/2 cup of low-glycemic basmati rice. Sweets A couple of pieces of dark chocolate.

Jessica Biel’s New Year’s Resolution:

• “Stop eating cheese and start eating kale. I eat way too much cheese. Kale is good for you and delicious with a little garlic.”

Check out this great workout created by Jessica's trainer: Circuit Workout by Celebrity Trainer Jason Walsh [3] as well as ways to get Jessica's arms [4].

Source [5]