I had those problems (and many more), but before going on any diet. In my case it was my heart not working properly anymore. I found in the end that the main problem was endocrine disruption. Sluggish thyroid, burnt out adrenals (I was under a lot of stress at the time) and low estrogen. I am not sure whether estrogen went down because of my thyroid and adrenal glands. But I am mentioning estrogen (and progesterone) because when I started an IP-like diet (hald IP, half alternatives), I lost weight fast and started to have TOM irregularities and other hormone-related effects. I think that IP can mess up your hormones depending on your state of health/age. This may indirectly affect heart function or it may affect aldosterone production, which is, I believe, dependent on your sex hormone balance. Aldosterone can also affect water retention. In any case, go to your doctor.