DH is on a diet, he's roughly following slimming world and is losing weight well. The problem is, he's gone from being really relaxed and sleeping like a log to having twitchy legs and being generally restless and fidgety in bed. He has always slept really well but is now up most nights with restlessness and twitchiness. He is convinced he's suffering some sort of withdrawal symptoms from something that's missing in his diet, but what could it be?