Being pregnant for 9 months and then giving birth takes a toll on a woman's body. To get your abs back you may need to change how you exercise.
Dieting without exercise will help you lose some fat, but you will also lose lean body mass - muscle. To help reshape your body you may need exercises that target the changes that occurred during pregnancy.
The forces of pregnancy and the weight of the baby pulls the body in different directions which changes the alignment of your body. When you are pregnant, your body is being pulled forward - Abs, shoulders, and head. This continues even after giving birth. For example, holding your child in front of you and pushing a stroller, you lean forward. You need to do less exercises that pull you forward and add movements that pull you back.
Three major changes occur to your midsection during pregnancy:
Weakened pelvic floor
Most women think they need to lose weight and do hundreds of crunches to lose the “tummy pooch.” As your pelvis tilts forward, it causes a swayed back and protruded tummy. This stays with many women even after birth. Once you are in proper alignment your stomach looks flatter without losing weight.
Most programs have you do crunches. By doing only crunches, it pulls your hip flexors in the wrong direction. This causes the muscles to become short and tight. It's the hip flexors that pull the pelvis forward in the front. You need to stretch the hip flexors while strengthening your abs. This draws the hips back into alignment, gets rid of your protruding tummy and flattens your abs.
The other sensitive area is weak pelvic floor muscles. Kegel exercises are a great way to tighten the pelvic floor muscles.
Whenever you do any ab workout, pull your abs inward by drawing your navel toward your spine. Imagine sucking your tummy in without holding your breath. This engages your inner core and pelvic floor muscles. Do your best to engage your core during all exercises even when you are focusing on your upper and lower body.