You need magnesium, sodium and potassium. The 5-8 week period at the start is usually when the water weight finally hits you and you flush out all the electrolytes your body had stored. You'll feel weaker than during any carb flu you might have had. You might get crampy. Perhaps even hunger is a symptom. Try the magnesium, sodium and potassium and if that's not the solution, well it'll help you anyway.
Female, 5'3", 48, Starting weight: 163lbs. Current weight: 135.
Starting bench press: 30lbs. Current bench press: 75lbs.