metabolism and weight loss

[zoom-zoom]

I've been training for a triathlon and am about 5-10 lbs above my ideal weight. Every morning I've been weighing myself right when I wake up to keep the readings consistent. Something interesting happened over the last few days:

Weds: AM: Swam .5 miles, PM: Ran 4 miles, Calories: about 1.5K
Thurs: AM: Zero weight change. Swam 1 mile. PM: Ran 5 miles. Calories: About 1.5K
Friday: AM: No weight change! Feeling pretty famished all day . PM: Swam 1/4 mile or so, ran 2.5 miles. Calories: Very hungry all day. About 2K, maybe more.
This morning: Lost 3 pounds.

What's going on? Why no weight loss at first, then I eat a bunch, and boom...weight loss? Can someone with a better understanding of fitness metabolism help me out?

 

[KaraCooks]

I think you're overthinking it.

First of all, what you ate last night or yesterday is usually not going to show up on the scale the next day unless it's sodium related water retention. Food doesn't metabolize into fat that quickly.

There are all kinds of things that can affect your weight over a 3 day period. Did you eat a little more sodium? Did you work out extra hard, causing your muscles to retain water?

Who knows. Seriously. Don't freak about it - let it go. Bodies do weird things when you put them under a lot of stress (like training for a Triathalon). Just keep on doing what you're doing and don't worry about it.

 

[zoom-zoom]

Ah...no I'm not freaking out or worried! I'm really just curious. I'm also a little bit annoyed that it doesn't make sense. My interest is more academic than anything...I'm a medical student and I'm taking biochemistry. I understand metabolism fairly well but this boggles my mind

I'd guess I packed on more muscle during those long runs and that's why I didn't lose much. I do normally register changes over a 24 hour period..whether it's a loss or gain, you can totally tell in both weight and appearance. Metabolism works fairly fast, in my experience...I could be wrong.

Mainly, I'm interested to know if eating more can cause you to burn more net calories than if you're starving yourself...or if that's a myth.

 

[Jynus]

well i can tell you this much. for the amount of work you're doing your calories are way to low. very possible you were starving yourself.

tour de france riders eat over 10000 calories a day. and that barely maintains them. a lot lose weight that should tell you something. your body needs energy to function. if it doens't get enough, it slows down.

however, that won't explain 3 lbs in 1 day. but something that can is: water weight...