Poor study with very limited parameters. To exert force requires energy which in terms of human nutrition is measured in calories burned. It is true that your basal metabolism (the amount of energy you need just to stay alive) is fairly constant and for individuals with low to moderate activity levels accounts for a very significant portion of their daily caloric burn. It is also true that nutrition (including calories consumed) has a huge impact on body composition. On the flip side, the greater the volume of work performed (physical activity) the greater the caloric expenditure. There may be some efficiency issues between individuals, but for a given individual, the more work you do, the more calories you burn, period.
Study be damned, if you burn more calories than you consume, you will lose weight, it is physiologically impossible to do otherwise as energy cannot be created, it can only change form. If the potential energy from your food = the kinetic energy of work performed, your fat stores will remain constant (notice I didn't say weight as weight can also include water/electrolyte issues). If our potential energy < the kinetic energy then additional potential energy from your glycogen and fat stores will be tapped and your fat stores will be depleted. The inverse is also true, that if your potential energy > the kinetic energy exerted, your body will store the excess as glycogen and fat.