In order for a person to lose body fat, that person must: take in more calories than they expend. take in less calories than they expend. take in the same number of calories as they expend. do none of the above.

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.

Ibelieve the answer is microorganisms within the body develop mutations, so d.hope i you out : )