As mentioned earlier, calories consumed and calories used up in exercise is not the entire answer to losing unwanted fat.
Ray Cronies, a NASA scientist, had researched that even if he ran a full marathon of over 42 km, he would only burn around 2600 calories burning approximately 300 gms of fat. So when he learnt that Michael Phelps, the Olympic swimmer, ate 12,000 calories a day, he analyzed that –
“In order for Phelps to burn those kind of calories above and beyond what his resting metabolic rate (RMR) was, and knowing that competitive swimming consumes only about 860 calories an hour, he would have to sustain more than 10 hours of continuous butterfly every day. Not even Phelps can do that”.
The answer was in understanding the thermal load of water (24 times more thermally conductive than air). Spending 3 or 4 hours a day in cool water helps Phelps lose more calories as heat. Also the effect of BAT (see below). Being in a pool of water at 270C for four hours could burn up an extra 4000 calories as thermal load. Of course even 2 hours of cold exposure (in 100C water) can burn up almost four times more fat than usual.
While calculating calories, it is not only calories consumed by exercise and storage that count. The human body is an open thermodynamic system and has other options to be considered. In addition to the Basal Metabolic Rate, calories are consumed through: Exercise – Heat loss through being in cold water / exposure to cold – Action of Adiponectin (a hormone secreted by fat cells), BAT and in matter excreted.
Not all fat is equal. White Adipose Tissue (WAT) and Brown Adipose Tissue (BAT) are different. BAT is NOT oxidized WAT.