I would really like to use the metric system. Can I do that?

Yes. In the log if you click the blue F button in the ‘Update BBT’ line – it will become a C, and your measurements will then be in celsius. Likewise, if you click the IN/LB button in the ‘Update BMI’ line it will turn into CM/KG and you will be able to keep track of your weight in kilograms and measure your height in centimeters.