after 15 days of losing and gaining and losing the same 2 to 3 lbs, I did what I called a mini-steak day. I had coffee in the morning (no half and half because it's P2), skipped lunch and had an 8 oz (raw weight) lean sirloin steak with all visible fat removed, broiled so there's no added fats/oils and with no salt used to season it. Along with it I had 175 g of roma tomatoes chopped up in 2 tbsp apple cider vinegar. The calorie total for the day was 350 calories. It dropped me down 2.6 lbs which was the most I'd lost in one day since the first week of that round.
Also in the later part of this long round I found my body seemed to react better with more protein. I was not eating fruit most days. I would increase my protein to 150 g or 200 g but always stay under 500 calories total for the day.