1. Learn how to effectively recruit your muscles! It won't matter what exercises you are doing if you aren't engaging your muscles correctly (and using as many as possible), it's all about the mind-body connection.
2. Your diet lacks protein. You can't build muscle if you aren't eating enough protein! To get the max benefits of your workout you need to eat a high protein snack within 30 minutes of exercising and a full meal within 2.5 hours of exercising. It's also important to get the right balance of carbs and healthy fats.
3. You aren't eating enough! This is a biggie. I'm a big fan of healthy snacks to keep you energised through the day, with no more than three hours between eating - so your body is constantly being provided with something to metabolise and build muscle. To put on muscle the amount of calories you eat must be significantly more than the calories you're burning.
4. You aren't getting enough sleep. As a new mum this is one I struggle with! You just have to do your best, if you get the opportunity for an early night take it!
5. You aren't doing the right kind of exercise and/or you are exercising to much! I recommend shorter sharper workouts, always under an hour. Keep the intensity high (relative to your fitness level). High Intensity Interval Training is very effective for body fat loss, increasing the after burn, boosting your metabolism - and also maintaining lean muscle.
Too much cardio, especially steady state, will hinder your ability to grow muscle. (Remember you need a caloric surplus to grow muscle).
Read about High Intensity Interval Training up on the blog HERE, the GREAT, the NOT GREAT, and WHY.
Read the blog "What can I do about my stomach?!, How do I get rid of my belly?!"