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What are the Lean Indices on my DEXA report?

bodyscan logo in office

On the front page of your Bodyscan report (bottom right) is a small table titled Lean Indices. There are two indices based on your lean mass here:

1.    Lean mass/height-squared  – Lean Mass Index (LMI)
2.    Appendicular lean/height-squared – Appendicular Lean Mass Index (ALMI)

First of all, lean mass on your Bodyscan DEXA report means all lean tissue, that is all soft tissue that’s not fat. Thus it includes internal organs but does not include bone. (Lean+BMC is lean plus bone, ie everything that’s not fat, or ‘fat-free mass’.)

Whilst lean mass is more than just muscle, it is an excellent proxy for muscle (about half or more of your lean body mass actually IS muscle) so they tell us how your muscle is distributed. We actually look at your muscle distribution and fat distribution in some detail during the consultation.

Your LMI relates to all the lean tissue in your whole body, while your ALMI is just about the lean in your limbs (your arms and legs).

A simple way to make sense of how high or low your lean indices are is to check your percentiles in the ‘AM’ column to see how you compare to a population of the same age and sex. While the percentiles on the report are for a US-based population, lean mass is pretty much the same across UK and US populations (and, anyway, we will compare your numbers with our UK database of more than 17,000 scans).

An AM (age-matched) percentile above 50 (50 is the median, the midway point of the population) means that you have a higher lean index than most people your age and sex. A bodybuilder will typically have AM percentiles in the 90s (ie, an indication of more lean mass than just about everyone his/her age).

If the AM percentiles for LMI and ALMI are close together then it suggests that lean mass (and therefore muscle mass) is evenly distributed around the body. If they’re far apart (eg, an AM percentile of 50 for LMI, and an AM percentile of 75 for ALMI), this suggest that the muscles in the trunk are less well developed than in the arms and legs. It’s like scoring 75% in a French (limbs) exam but only 50% in a French & German (limbs + trunk) exam.  Clearly, your German (trunk) is dragging you down. So go and work on that German trunk!

For help on muscle-building, download our free muscle guide.

A DEXA scan at Bodyscan

When you have your Baseline DEXA scan with Bodyscan, your consultant explains all the numbers on your report, including your lean indices. By plotting your own lean indices against our database of 17,000 UK DEXA scans, we’ll be able to provide ‘hidden’ information about your muscle distribution across the regions of the body, in addition to left-right imbalances.

If you’re searching for a DEXA scan in the UK then you’re in the right place! Book an appointment with Bodyscan today. We have two easy-to-reach London clinics – in the City just steps from Bank station, and on Marylebone High Street, a short walk from Baker Street tube.

If it’s your first time with us, please select our 60-minute Baseline Scan with Consultation. This includes the scan, a printed and emailed report, detailed notes, and the all-important post-scan face-to-face consultation. At the end of the appointment you’ll have the option (and, we guarantee, the motivation) to purchase follow-up 20-minute Progress Scans.

The consultation will bring your results alive and give them real meaning. We’ll use our body composition calculators to process your DEXA scan data. From this, we’ll be able to discuss your recommended calorie intake and potential targets for fat loss and muscle gain. This video explains why a DEXA scan is a better way to work out your calorie requirements – because your lean mass is the primary input to the formula (and lean mass is the biggest burner of calories).

Write to us at [email protected] for more information on DEXA scans in the UK, or you can watch our deep-dive DEXA information videos here.