Iud rapid weight lost

I have had the mirena iud for like a year and a half now and quite a lot of weight without really changing anything i was actually pretty happy about it but everybody thinks I look either sick or strung out witch I only smoke pot and

I’m wondering if this is a side effect or should I start to get concerned I’m 137lbs and I’m normal in the 145-150’s

*** I also had a baby almost 2 years ago I was 210 when I had him

*** I did a low carb diet when I was like 8months

Pp only did it for a month since then I have not been dieting