Clinically macrocal and kilocalorie mean the same thing, they are just called different things. 100 macrocalories is 100 kilocalories, there is no difference, but 100 macrocalories and 100 calories are 1000 times different. The basal metabolism alone can reach 1,200-1,600 calories per day, or 1.2 million to 1.6 million calories. In general, food calories range from a few dozen to a few hundred calories, and exercise burns anywhere from a few dozen to a few hundred calories. One calorie is defined as the number of calories required to raise one gram of water by one degree Celsius at one atmosphere of pressure, and this caloric value is so low that a calorie is a very small unit, much in the same way that a millimeter is a very small unit in the measurement of length. 1 gram of sugar and protein both produce about 4 kilocalories, or 4 calories, and the same amount of fat produces many more calories than sugar and protein, so it is important to control your fat intake when you lose weight.