MAC, unwell with rapid weightloss

I lost 50lbs before I was diagnosed. It’s not unusual to loose weight I am told. Body always fighting infection uses a lot of calories.
I’m good now weight wise. I eat on a schedule whether I’m hungry or not.

@westcottkm3040 You are 100% correct. I lost over 20% of my body weight in the beginning, and it was explained to me by my ID doctor that my body is fighting so hard to fight the infection, the number of calories I was consuming was not close to enough. Even now with three replacement Ensure meals in between meals, I struggle with keeping weight on. Many general practitioners don’t get it which is unfortunate. Mine trained in infectious disease so she totally understood. Unfortunately for me- fortunately for her she got a great job in Springfield, Massachusetts as an ID doctor. I’m back to a nice GP who never heard of MAC till me. Luckily I have my UMass specialists! (Irene5)

I lost weight after finishing the big 3, likely due to what previous replies have indicated- body fighting off the infection requiring more calories than your normal baseline. The heavy antibiotics can also throw off gut biome. There was a great seminar recently by nutritionist Michele McDonald, formerly with National Jewish Hospital discussing protein bars and supplements. She made a point to state higher calorie dense shakes can be beneficial when trying to gain or maintain weight. I just ordered Kate Farms which was one of her top recommendations. My gastro also suggested supplementing with MCT oil, with the ok from my primary care as it’s high in fat and highly digestible. You can ask your dr for advice and approval before adding supplements, this is just information I was given.

Also lots of small meals and snacks whether you’re hungry or not. I believe it was Sue who said she would ensure she had at least 100 calories every hour.

@irene5 thank you so much for taking the time to respond, I have been struggling for the last 8 plus months with multiple infections suspected heart failure and the rapid weight loss with no answers. I asked multiple times if this could be connected to my MAC, and was told a firm no every time.

I have lost a lot of weight while harboring MAC. I don't know when exactly the MAC started gaining the upper hand, but I suspect it was when I started having trouble maintaining my normal weight (115-120) and that was years ago. I would lose during an exacerbation, then slowly get back a few pounds, but not all. Then another exacerbation, more loss, and not enough regained - a few cycles of this over the last few years, and I'm trying to stay above 100. Sam5826: from my experience, MAC can impact weight, definitely.

@sam5826 Because you mentioned being on the big 3 for 2 years (4 years ago) then failing bronchoscopy, which I take to mean, you still grew MAC. With the Jan 2026 pneumonia, plus subsequent infections, did they send in Sputum to check for MAC levels and/or an opportunistic bacteria? Are they treating these infections with broad spectrum type anti-biotics? Sorry you are having such a challenging year!

Hi, thanks, and yes, each infection with a broad spectrum antibiotic. No, no sputum or Bronchoscopy for MAC levels, just being passed from Doctor to doctor. After doing my own research, and connecting with this group, I have just gotten a referral to the Mayo MAC clinic, so fingers crossed for some answers , it’s been a really tough year.

@ursala7 Thanks Liz, sorry to hear your struggles. I was heavy before and struggled to lose weight , so thankfully had lots to lose, but at some point I’ll need to stop losing.

Hi y'all, just a quick comment on gaining weight back....
I unintendedly lost 10 pounds in May. It took me a month to put the pounds back on because I did it slowly, instead of just eating cheesecake. My helpful tip is this: put everything you eat (and plan to eat) into one of these online counters (I used the free version of cronometer.com). At first I was eating like a big dog and couldn't understand why I wasn't gaining weight. It turned out that I really couldn't effectively estimate calorie count. After putting in my targets (it can keep track of carbs, proteins, fats, and calories burned too) and my weight goals, it kept me on track. I was able to gain the weight back with a healthy diet and I've been holding steady ever since July, which is when I stopped using the program. I'll go back to it when/if needed.

Thank you!