The diet is the start. Craving Sugar is normal - your metabolism is lazy why should it make up Sugar from fat when it can simply have you swallow it. Once you have spent a few days without eating Sugar you won't crave sugar anymore. The key is to teach your metabolism to rely on the fat you eat instead.
At first it is important to identify your personal intolerance. Listen to you body.
It is likely that you need to supplement on magnesium. Severe constipation and muscle weakness are due to magnesium deficiency- Epsom Salt into a hot bath is another way to supplement in magnesium. I would suggest you do both.
Once you are comfortable with the diet and no longer crave sugar,
I would recommend a Bowel Cleanse - look at the post I wrote fro Kiki above for details.