Described are apparatus and methods for electrically modulating a nerve in a mammal. An electrical signal that includes a signal intensity pattern and a signal frequency pattern is delivered to a nerve. The combination of the signal intensity pattern and the signal frequency pattern is effective to result in weight loss, fat loss, and/or lean-mass gain, in a mammal. In some embodiments the nerve is modulated in response to a physiological parameter. In some embodiments, the physiological parameter is measured by a sensor.