Muscle testing, also referred to as energy testing, is a way to use the subconscious mind to give you feedback.
Those of you who know how I work, know that I use a pendulum to muscle test, but a pendulum is not necessary and everyone can learn how to do this. It's a very simple and valuable tool to have. Initially, it takes a bit of practice to "get out of your own way", but once mastered, you can easily get information directly from your body on things that will benefit you, like supplements and food. You can also get yes and no responses to help you with decision-making.
A Simple Technique to Self-Muscle-Test
If you're new to this practice, this is the easiest method to learn first:
"Stand and Sway" Method:
Stand in a relaxed manner with your feet about shoulder width apart and keeping your knees relaxed. Some people find it helpful to close their eyes to avoid visual distractions. Say: "Show me yes" and you should feel yourself either start to lean forwards or want to lean forward - the movement does not need to be dramatic or intense. Then say: "Show me no". You should feel yourself either leaning backwards or wanting to lean backwards. You can also do this to test supplements: Hold the item to your chest, in the area of the thymus gland and ask: "Is this product beneficial for my body?". You should sway forward for a "yes" response and backward for a "no" response. If you ever see anyone swaying back and forth at health food stores while clutching a product, now you know why!
For more information on muscle testing, check out this wonderful video of Dr. Bradley Nelson explaining the concept and demonstrating how to muscle test: