"I don't eat that much"  "It's a genetic thing"  "I can't exercise because of my knees/my weight/my preexisting conditions" it can be very extremely frustrating. Also missinformation about nutritional values, "starvation mode", that drinks contain calories as well.  Absolute inability to cook, some have never cooked a single meal in their life, don't know that you can make food yourself, don't know how do boil an egg, make potatoes, cook rice, don't have to consume prepacked meals.. That it's cheaper to make things. Some don't have a pan. Or an oven. So basic stuff, it's like starting from scratch. They have to keep a food diary, which sometimes show they can't count or weigh stuff, or even write properly. Massiv lack of education sometimes. Where to start. it's sometimes more of a life coach/ life skill training more than losing weight.