zlacker

If you want your refrigerator and freezer to save energy then make sure there is as little empty space in them as is possible. It makes the entire system more efficient, stable, and reduces the impact of opening the door.

>>akira2+(OP)
The only part of that which is true is the bit about opening the door, since there's a smaller volume of air which can mix with the outside air.

That said it makes such a small difference that it's really not worth worrying about, in fact you might lose more energy keeping the door open longer to find the thing you want in your packed fridge.

>>Turska+zi
Higher thermal mass is higher thermal stability and less compressor short cycling. If you have a chest freezer this is pretty easy to notice.

Air is a particularly poor conductor of heat, your hands touching the product to move it around is doing more damage than anything else. Your fridge thermometer only measures air temperature, not product temperature, which is what you actually should care about.