Depth and rate of compressions on an obese adult is:

The depth of chest compressions on an adult, including an obese adult, should be at least 2 inches (5 cm) but not greater than 2.4 inches (6 cm). The rate of compressions should be between 100-120 compressions per minute. This is according to the American Heart Association's guidelines for CPR.

Here are the steps to perform chest compressions:

1. Position the person flat on their back on a firm surface.
2. Kneel beside the person's neck and shoulders.
3. Place the heel of one hand over the center of the person's chest, between the nipples. Place your other hand on top of the first hand. Keep your elbows straight and position your shoulders directly above your hands.
4. Use your upper body weight (not just your arms) as you push straight down on (compress) the chest at least 2 inches (approximately 5 centimeters) but not greater than 2.4 inches (approximately 6 centimeters). Push hard at a rate of 100 to 120 compressions a minute.
5. If you haven't been trained in CPR, continue chest compressions until there are signs of movement or until emergency medical personnel take over. If you have been trained in CPR, go on to opening the airway and rescue breathing.