Are there any Men with low BMI here around 16 BMI?

mrsingle
Since late childhood I've had very low BMI and no matter what I ate or diet I tried I never was normal weight. I am 6'2" 125 pounds which is anorexia weight but I know I don't have an eating disorder. Often I get anemia symptoms when I don't eat enough like if I'm active or unable to eat like if I'm out somewhere.
I was genetic tested and found positive carrying the gene for Marfans syndrome but doctors say I don't actually have it just carry the mutation, so this might explain the very thin body frame. However I also deal with severe stress and anxiety and that can affect weight gain, and when I do eat a lot I get stomach pains and painful constipation as if my body rejected eating super large meals in a sitting. Even eating huge meals doesn't help, and I've read the foods to gain weight and I love most of them and eat them but it hasn't helped. Even protein shakes do nothing I just poop more (TMI I know) and don't put on weight.

Its scary, and people assume i starve myself they don't believe It's something else.
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Are there any Men with low BMI here around 16 BMI?
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