Below is all i found on low potasium...nothing referring to weight gain...except water weight...hope this helps.....
Low Potassium Symptoms
Usually symptoms of low potassium are mild. At times they can be vague. You may have more than one symptom involving the gastrointestinal (GI) tract, kidneys, muscles, heart, and nerves.
Weakness, tiredness, or cramping in arm or leg muscles, sometimes severe enough to cause inability to move arms or legs due to weakness (much like a paralysis)
Tingling or numbness
Nausea or vomiting
Abdominal cramping, bloating
Constipation
Palpitations (feeling your heart beat irregularly)
Passing large amounts of urine or feeling very thirsty most of the time
Fainting due to low blood pressure
Abnormal psychological behavior: depression, psychosis, delirium, confusion, or hallucinations.
We must have been watching the same TV show AR! I also seem to remember recently reading ( or hearing) a ton of information on the potassium thing.
I just don't remember where? If my mind serves me well - it said or I heard or read - something about a large amount of potassium deficient people were complaining about weight issues when really it was water retention.
I too can not put the sources together though.
I do know just assuming potassium is a problem and taking it without testing can be very toxic. Mineral supplements if taken to much can be dangerous in general.
In the question on gaining weight - I was Graves and lost rapid amounts of weight.
I lost 37 pounds in 2 mths before storming and I ate like a horse!
It's a bit of a stretch, but you could ask to have your potassium, calcium, and magnesium checked.
I read something about potassium and water retention the other day, but it's already a fading memory.
I read a post today on the forum that said 11% of hyperthyroid patients gained weight rather than losing weight. I have NO idea where that data came from.
If nothing else, I threw out a few thoughts someone else can chew on and run with.