How to accurately measure muscle mass versus body fat?

Question

I want to know how to calculate how much muscle mass one has as opposed actually body fat.

Answer 1

When we interview Get Fit Guy, Ben Greenfield for the blog, he mentioned a an ultrasound device which he describes more in his podcast (around the 45-minute mark) with the creator of the BodyMetrix.

Intelamterix makes a product called BodyMetrix that can accurately scan your body fat percentage and track your fat loss and muscle gain. The way the BodyMetrix works is by using ultrasound waves to penetrate the tissue and detect the reflections that occur at different tissues boundaries (such as between fat and bone and bone and muscle). Taking measurements at multiple points of the body can give you and accurate percentage of body fat.

Compared to other methods, the BodyMetrix:

• Does not require a trained specialist or certified technician to operate
• Measures consistently regardless of caffeine, alcohol, or hydration levels
• Is more comfortable than pinching (with calipers), being fully submerged underwater (underwater weighing), or being sealed in a small chamber (air displacement)

The product's faq states:

• Assessments can take 2-10 minutes
• Training materials are provided (user's guides, videos, or live web training for Pro users)
• More accurate than skin fold calipers or bio-electrical impedance devices
• Results are comparable to underwater weighing and air displacements
• Non-invasive and portable
• Safe for children (but not intended for use on children under 6 years)

There are two versions of the BodyMetrix, Personal and Pro. It is quite costly ($495 for the Personal version) and even more so for the Pro version ($1895).

The software itself tracks measurements and can generate reports. Screenshots of measurements and trend from the software (taken from IntelaMetrix's website):

Answer 2

A low dollar scale on Amazon is the Omron HBF-306C.

I don't work for Amazon, so if you can find it somewhere else I will not be hurt. ;)

Answer 3

Body fat measurement scales work well enough for your purposes. I've used one for years.

However, I suggest you set yourself up a protocol so that you are consistently measuring. I do it every week, on a Tuesday to allow a day after my last long run on a Sunday. I do it in the morning, before breakfast but after I've used the toilet.

I write the results down in a little notebook and use it to tell me where I am in terms of muscle and fat.

Answer 4

Short answer is that you can't. You can calculate body fat%, unfortunately the amount of mass that is not fat is composed of things that do vary such as water weight, amount of undigested food, etc. Considering even the difficulty in just measuring body fat, you will do good just to keep track of that.

Assuming you keep your diet consistent, you can keep track of weekly changes in lean mass to get an idea of which way things are changing.

A less sophisticated way is to take flexible tape measurements of all your major muscles that you want to track. When things are growing in the right proportions, you are doing well. If not, you'll either need to change your training or your diet.