Exercise calorie question answered

someone recently asked me in a private email whether they should eat their exercise calories, I get about 5 or so emails a day asking this, but I'm busy today and really don't have a ton of time, but I liked my response to this person, so I'm gonna post this (without any names). Now, I'm not a doctor, nor have I any formal training or certifications in diet or nutrition, but I've done quite a bit of self study on the subject, and done a lot of observation on here, at home, and with friends. So take what I say for what it's worth. Anyway, here's what I wrote. And remember, everyone is different, your situation may or may not mirror it, it's a generalization based on accumulated study and research, bear in mind there's always the exception that lies outside the normal boundries.

So I was asked about whether to eat exercise calories, and this is what I wrote back:

exercise calories, ok. so couple things to know about exercise calories. First is, MyFitnessPal doesn't include them in anything until you actually enter them. So when MFP calculates your calorie deficit, that deficit is based on your TDEE (Total Daily Energy Expenditure), your TDEE does NOT include exercise. In other words MFP makes a plan, the plan doesn't have anything to do with exercise. If you DON'T eat your exercise calories you are actually creating a larger calorie deficit than MFP created for you. Now, I don't know your weight or any other numbers so I can't say one way or another whether your body can support a calorie deficit greater than 2 lbs a week, but I'll say this, anything over 2 lbs a week is EXTREMELY aggressive, you essentially must be morbidly obese to support this.

Things happen when you create a calorie deficit that is too big. Things you don't see right away but catch up with you in a month or 2 months or 3 months...etc.
Here's what happens to someone who tries to lose too much too fast:
-they change their eating, and start logging food and exercising, for the first week or 3 everything is great, they are hungry, a little tired, but otherwise, loosing weight at a marvelous clip (maybe 3 or 4 or even 5 lbs a week).
-After a few weeks, the weight loss slows, the hunger doesn't, and if they continue, their mood and their will power start to fray.
-After 6 weeks or so, plateau's start to set in, because they were so aggressive in the beginning, after the really easy fat was gone, and the water weight was removed, the body started to eat it's own muscle, which lowered their metabolism, combine that with eating far too few calories in the first place and you have what's commonly known as starvation mode. People don't see this coming, it's not a drastic change, it's gradual. They are no longer hungry even though they only ate 1100 calories that day, they are tired, but they are ALWAYS tired so they don't notice, their mood is just plain bad, and they are weaker.
It doesn't matter how much weight training and cardio you do, if you don't eat enough, you're gonna regret it. At this point they are damaging organs, reducing muscle mass, encouraging fat storage, and weakening bones.

So I says this, I'm not telling you how to lose weight, but after 3 years on here, my own weight loss, countless hours of research, and watching people suffer and fail over and over and over, I say please, don't try to do it too fast. It's a path to failure. Take your time, learn your body, let your body adjust to the new food, give it fuel, don't try to lose too much too fast. Not only do the above things all happen, but if you lose too fast, things get saggy (all kinds of things), because the body doesn't have the time to shrink the extra skin.