I''m 14, why do i gain weight so quickly?

I''m 14 and I don''t understand how i gain weight so quickly. Like sometimes I can gain 5 pounds in a day, i count my calories and i only eat like 300-400 more than i burn off and i literally gain that much weight no joke. I dont understand why. But I have restricted my calories in the past and lost a lot of weight but I have recovered and its been a year since then. I don''t get it.

How to Get Motivated to Lose Weight

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First of all that 5 lbs in one day,
do you weigh yourself in the same place at the same time each day?
there are all sorts of variables here.

Think about your "weight" as just a number,
what really matters is can you Function, that is
can you run, ride a bike, climb stairs ( or? ) whatever ... rejoice in what works.


Smile ................................................................ Mother Nature Loves U!

• The dramatic weight gain is probably just weight from the food you ate, I mean it has mass when it goes in your stomach so the mass will stay until it''s broken down.
  
  Mine?
  http://answers.yahoo.com/question/index?qid=20130128183923AAePGAN
• Try weighing yourself weekly.. You only lose weight if you BURN MORE CALORIES THAN YOU EAT... It also can be alot of water weight..
• If you are eating more calories than you burn, you will gain weight every day. That''s just how humans work. You can''t eat an excess of calories unless you are okay with gaining weight.
• Well if its all healthy it burns but also stays and builds muscles like maybe on your butt or something. If you are not sore a lot it is because your muscles are getting exactly what they need to help them recover