Trainer said EAT MORE

sunnybeaches105

I'm 5'10", right at 200 pounds, and I'm currently dieting down with a 2050 NEAT, meaning I'm often consuming 2300-2600 calories per day due to the additional calorie allotment from exercise. Metabolic damage takes time to develop and it's not something to get too excited about, but at your size you almost certainly should be eating more if you want to avoid losing muscle mass.

ETA: Let me add that you do need to eat nutrient rich foods, but the point I think your trainer may have been making is "clean" eating isn't a good guide, and you need enough energy to fuel your workouts and maintain lean mass. Focus on upping your calories using the MFP calculator to lose a bit less than you're targeting now. Get plenty of protein and good fats. For weight loss, calories matter. For general health and body composition, what you eat also matters, but it doesn't need to be "clean" (it, or more accurately your overall diet, needs the right amount of macro and micro nutrients).