Measuring your body composition — how much of you is made up of water, muscle, and fat — is the best way to assess whether you're gaining fat or muscle, Berkow said. King noted that many gyms do a body composition test of some sort before people start programs in order to get baseline values and therefore set realistic goals. Some tests include the following:
- Bioelectrical Impedance Analysis (BIA): Body composition can be measured most easily with a BIA, "where harmless electrical currents through your body are used," Berkow explained. You even get a BIA scale that you step on or hold in your hands, but Berkow said to make sure you use it on an empty stomach and when you are hydrated "since being dehydrated can erroneously send up your body fat percentage reading."
- Skinfold calipers: These "pinch tests" can be used to measure gains or losses in body fat.
- DEXA scan: The dual-energy X-ray absorptiometry (DEXA) scan is a radiological scan used to measure bone density. It's the most accurate way to measure your body composition, but is often less accessible than a BIA scale, Berkow said.
- CT scan and blood tests: These will indicate whether you've developed an increasing amount of visceral fat, and you or a doctor can proceed to take measurements of your waist circumference since most often, excess visceral fat can cause protrusion of the abdomen. You can read more about that here.