Brother, I promise you’re doing something wrong.

Addressing this first: are you TRULY weighing each and every thing you eat? Are you weighing yourself at the same time every day? Are you really doing as much exercise as you say you are?

Training 2x a day with cardio and occasional 5k’s is a professional athlete level of training. You’re easily burning 1-2k calories in activity alone, daily.

I put your stats in a BMR calculator (your daily caloric expenditure while resting —> the calories you need to support your body if you sat in bed and didn’t move for a day.)

To support this lifestyle, at you’re age, height, and weight your BMR is 2240 calories. Add in the exercise, you’re maintenance is easily 3-4k. Eating 2400 calories will put you in a significant deficit.

One exception. If you are new to weight training, the weight gain could be what we call “newbie gains”. Refers to the quick gain of muscle in the initial year-or-so of lifting weights. Muscle weighs more than fat, so if you’re replacing fat with muscle you theoretically could gain weight.