Exactly the same happened to me last night ! I put it down to the bedroom being cold as I hardly ever get cramp unless my legs get cold in the night. But I wonder if it might be a VLCD thing although I am on week 8 ?
Holland and Barrett Chelated Potassium 99mg one daily, preferably with a meal (!).I picked this up from a low-carb board when I low-carbed before and I have started taking it again othewise I get the cramp!
A few people are prone to cramp while using the Diet as their Sole Source of nutrition. It is not caused by the diet itself, but by the increased throughput of fluid in the body’s tissues. The muscle spasms result from changes in sodium levels as the water shifts between cells. The remedy for most people is to keep warm, whilst a drink of slimline tonic water just before bedtime may also help, as it contains quinine – as may "Crampex" tablets.
The level of quinnine phosphate for leg cramps is very low and should not pose a risk, however, pharmacists would advise accordingly and if there were any contraindications they would not let you have the product.