Oh boy, Lyme and weight - the subject I hate the most!! I have been carrying too much weight ever since I had to seriously slow down - I hate it!! Lyme also messes with hormones, and not just estrogen and testosterone, but the hormones that regulate our thyroids and adrenals as well. Symptoms of thyroid or adrenal issues can be weight related as well.
Twinkl, do what you can to bring awareness to your friend as best as you can - but also know when to leave it alone, as Achievinggrace was saying. Some are just not going to believe they have Lyme - period - end of story. It doesn't make any sense to me, but it still happens.