The first week is definitely the hardest, it gets easier.
I am on thyroid med and did fine for a year of P1, but I have a thyroid.
I think I might have had more fatigue and needed more rest than others - hard to say though, I’m not in their body
. A lot of people report having a lot of energy on P1 and I definitely didn’t have that. Also my loss rate was about average, not faster or slower than others.
Maintenance though I think possibly has been more challenging for me to maintain the loss - I have had trouble with blood sugar swings but that might be very unrelated to the thyroid. I have had to keep things still pretty low glycemic and eat small amounts every few hours.
Given those details though
overall IP has been a great experience for me and I am much healthier at a healthy weight than being overweight, and about 75% of my health problems have improved, and the remaining 25% are much easier to handle without the extra weight.
It was definitely worth it.