Weight is relative to the gravitational force that acts on the object.
Since there is no external gravitational force acting upon the planet, the planet has no weight.
It has, however, a mass, and yes, you can increase the earth’s mass.
In fact, it gains weight constantly due to meteorite impacts.

@ragingloli
I meant “it gains mass constantly”

No…only outside sources like meteors or comets can add to our weight to our planet and lately it is a losing battle as we eject 1,000’s of pounds of satellites and rocket booster junk into space every year.

It wouldn’t be practical. Eating till you weigh 500 pounds just relocates mass from the food you ate into your body. It doesn’t thange the total mass on Earth at all. Likewise, while Earth’s population has grown from the first humans to now around 7 billion, that added no mass. We just consumed resources and other life forms, each of which had comsumed resources, to att all those new people.

But, as @ragingloli said, the Earth gains a bit of mass each day from dust from meteors that burn up in the atmosphere and from the occasional meteorite that makes it through the atmosphere and strikes Earth.

The closest we humans have come to deliberately adding mass to the Earth was when we flew to the moon and fetched some moon rocks to study. But I am sure we left more in space than we brought back. We would have to build a vehicle like the Shuttle capable of launch with recovery of its boosters, flying to the moon or beyond, landing there, then returning to Earth of we wanted to add mass to the earth through human action. It’s easier to just let the meteor dust do it. :-)

Let me correct one wrong assumption. Someone does not die every time someone is born. The population of the earth is growing exponentially.

@marinelife I’m glad you picked that up. I had meant to, and forgot.