H.L.
This post is just in case other areas besides eating healthy and working out could be contributing to your situation. I do not know you so I am not sure how much or if any of it applies, but anyway, this is good information at any rate.
As a mother, I was delighted to learn the liver has an amazing capacity to store an entire year's worth of vitamins (which is kind of a complex science which I won't go into right now). However, if we are B vitamin deficient it can halt weight loss because B vitamins are a crucial contributor to the chemical process of burning fat. It takes B vitamins, carbohydrate, and fiber combined with exercise to unlock our fat burning power. Many people do not realize that if the mathematics are out of balance, such as when we eat too much carbohydrate, our body can do nothing but store the excess energy as fat until enough B vitamin and fiber are present to release it.
Besides this, there are four major contributors to storing body fat. Each of the four contributors, which I will list momentarily, all trigger the same hormone when present. The hormone is called adreno-cortisol. Adreno-cortisol is released by the body to harvest muscle tissue for protein derived glucose in order to keep our brain functioning or to super produce energy on demand. When one is sleep deprived or ignoring hunger signals, adreno-cortisol is released to harvest muscle to keep our brain functioning. When one is angry or afraid, adreno-cortisol is released to fuel our sudden flight or fight response. A lifestyle of going to bed late, ignoring when we are hungry, or being stuck in negative coping cycles is obviously very unhealthy, but sometimes a hard thing to break out of. The other option is to bite the bullet, teach our kids to treasure healthy sleep, eat high fiber, whole foods, and seek excellence in coping. This kind of lifestyle will abate adreno-cortisol, which, when released, not only attacks our muscle mass, but also our entire vascular system leaving us open to heart attacks and strokes eventually.
The best way to rebuild a compromised muscle mass is to do weight training, but it helps a lot to have all the other aspects that might otherwise prove counterproductive in order too.
One other item of good news is that by 6 weeks old an infant's brain becomes capable of REM sleep. Between then and when they become 3 months old, they can be successfully trained to sleep through the night. This not only allows your baby to benefit from the growth hormone and neurotransmitter repair that only happens in deep, uninterrupted sleep, but it will also allow you to have that sacred, necessary kind of sleep too. Babies, whose mothers cultivate this kind of sleep, have also been researched to learn language faster. I have no doubt your thyroid could possibly benefit from the repairing, healing benefits of growth hormone.
I will stop here to avoid sounding like a never ending medical journal, however I hope the information has been at least a little bit interesting and helped to tie together some of the mysteries behind motherhood.