It does use more gas, but the amount is negligible. For example, if your freezer is at 0 degrees Fahrenheit and you defrost a pound of frozen meat for 2 hours, it will use about 6 cubic feet of gas. However, if your freezer is at 20 degrees Fahrenheit and you defrost a pound of frozen meat for 2 hours, it will only use about 1 cubic foot of gas. So the difference in gas usage between defrosting at 0 degrees and 20 degrees is only about 5 cubic feet.