[Jet2]

If everything exists on Earth are from Earth, since mass unchanged, does it mean Earth will always weight the same no matter how over populated we are?

[Zythryn]

The exact weight of the earth changes daily, although it is a tiny tiny tiny fraction of the overall mass.
This is not due to population growth.
When people are conceived, and undergo growth, it is by absorbing nutrients. So we don't really add to the mass of the earth, we just have less mass from our food source and more from us humans
The earth also gains mass from incoming space debri (both ours and natural) and looses some gases from the atmosphere each year.

I suppose there may be some mass gain at some level from plankton using sunlight to create mass?? Not really sure, but that single cell level MIGHT be an area where a tiny bit of energy is turned into mass?

[Turtle]

Originally Posted by Jet2

If everything exists on Earth are from Earth, since mass unchanged, does it mean Earth will always weight the same no matter how over populated we are?

There is a steady fall of meteoric dust to Earth, so Earth's mass slowly increases, and past meteor/comet impacts likely knocked some of Earth out into space which reduces our mass. The population as you say doesn't matter.

I find widely varying estimates of the amount; this article puts meteoric dust infall at 30,000 tonnes annually. (Note: 'tonne' refers to 'metric ton', which is 1,000 killograms)

...Every year about 30,000 tonnes of space dust fall into the Earth's atmosphere without any serious effect, says Mr Kortenkamp.

These particles reflect sunlight, effectively shading the Earth and causing some cooling. ...

BBC News | SCI/TECH | Space dust 'did for dinosaurs'

[Thunderbird]

Originally Posted by Zythryn

I suppose there may be some mass gain at some level from plankton using sunlight to create mass?? Not really sure, but that single cell level MIGHT be an area where a tiny bit of energy is turned into mass?

I believe sunlight is just a bonding agent between water and carbon during the photosynthitic process, as far as I know there is no gain in mass.