I've typed up the food I eat on many occasions and it's been about 3500kcal a day.
I have recently started to gain weight though and it was me going low carb + high fat that did it. I only eat a high amount of carbs less than 4h after training. Looking at the possibility of hyperthyroidism that would make sense... especially when I was really ramping up the calories each day and getting leaner, I was basically getting them through simple sugars (IE a slab of coca cola a day).
Even if the tests do come back with elevated T3 production I am tempted to just leave it be until I get serious problems. Despite what AusBB thinks there is nothing really wrong with my weight lol. Looks like a keto style diet is the way forwards for me anyway. Or at least significantly upping the amount of fat I eat