"Energy gain" refers to the acquisition or increase in energy levels. It signifies an improvement or boost in the amount of energy available, which can be used to perform various tasks or activities. Full definition
The lack of healthy carbs, fats and proteins will affect the amount of energy gained from eating the food and can in the long term influence the maintenance of muscles. (theeverythingdogsite.com)
Firstly, to be sustainable, the amount of energy gained in growing and utilizing an energy crop must exceed that used in producing the crop. (greenfacts.org)
Just because you add in another term which has temperature in it does not mean that the total energy gain changes. (gfdl.noaa.gov)