Therefore energy storage per unit mass of adipose tissue ≈ 7.2 kcal/g
Common units for mass and energy...
1 Stone = 6.35029318 kilograms
1 Stone = 14 pounds
1 Pound = 0.45359237 kg
1 kcalorie = 4.184 kjoules
1 Kilowatt hour (KWH) = 3.6 megajoules
1 Kilowatt hour (KWH) ≈ 860.42 kcalories
Note. a kilocalorie or kcalorie is the amount of energy needed to increase the temperature of 1kg of water by 1°C
Body fat energy per various units of mass
8.37 x 10-3
A typical human expends approximately 2000 calories per day = 8368 kjoules ≈ 83 kcalories/hour ≈ 96.851 Watts (joules/sec). The human brain typically accounts for 20% of that energy, so a human brain runs on about 19 Watts.
Running expends about 720 kcal/hour  depending on weight, speed and fitness level. 720kcal/hour = 0.2 kcal/sec = 836.8 Watts (so approaching the energy of a 1 bar/kilowatt electric fire, or about 9x the average energy expenditure rate). 1 stone of body fat is equivalent to about 63 hours of running or about 380 miles! You would of course not be able to run that far in one session due to tissue damage caused by exercise, requiring protein and rest to repair (and of course the need for sleep).
Walking at a moderate pace of about 3mph expends about 250-300 kcal/hour  depending on weight, speed and fitness level. 1 stone of body fat is equivalent to about 166 hours of walking or about 500 miles!