Because it is not 4000 cal of salad. It's 200 cal of salad, 2000 cal of ranch & the rest is all the shit that doesn't belong in a salad and could be seen as a dish of its own. Salads are dumb for weightloss, anyway. When people say they just eat salad to lose weight, I immediately assume that they don't know wtf they're talking about or they say salad to lie to people because it is a common trope. Yes, it is low calorie but it is not sustainable / doesn't keep you full and fit on its own. Just eat chicken & fish while being in a deficit of calories, and add salad to it so you can poop normally.