Can Someone Please Explain?

I've heard about the "NEVER under ANY CIRCUMSTANCES eat ANYWHERE below 1500 calories if you're a teen!" I'll accept it and eat by it, but first I'd like to understand why.

So my BMR is supposedly around 1900, and I've eaten 1200 today. A deficit between 500-1000 calories is supposed to be what you eat to lose 1 lb. a week, I understand that. But why is a 700 calorie deficit such a problem? I plan on eating a 300 calorie dinner, don't worry, so I'm just wondering for the sake of wondering.

I think that calorie recommendation comes not so much because you HAVE to have that many- but as a teen you're still developing and growing. It seems that is about how much you will need to consume to get enough nutrients to continue to develop at a healthy rate. In the developmental years, it is never recommended one diets, for that reason.

It is good that you want to understand as this works.  The more information you have, the better you will be at making good decisions about your diet. 

Aside from the need for nutrients to grow and develop as spacelogic mentioned, My understanding is that the younger you are the more calories you burn naturally.(Maybe that's because of the growing.)  So, you need more calories because you burn more calories than a 30, 40, or 50 year old your same weight, height, and activity level. 

You need a deficit of only 500 calories to lose about 1.5 lbs. per week.  1.5 lb. loss a week is recommended because it is sustainable over the long hall.  People who cut way back as you are suggesting cannot sustain it and the yoyoing begins. 

Another reason to have no more than a 500 cal deficit to start is that after dieting for a while, as you probably know, people tend to plateau.  If your calories are already so low that you body thinks you are starving, you have no more calories to cut out.  Your body's response to lowering your calorie count even more will be to become more efficient and burn less calories. 

By the way, I can't imagine what a 300 calories dinner looks like.  It's good you had a nice breakfast and lunch. 

Random question, but as an 18 year old would i still classify as a 'teen'.

Original Post by kay90:

Random question, but as an 18 year old would i still classify as a 'teen'.