Almost everyone who comes to Bodyscan wants to know their body fat percentage (BF%)
But whilst BF% is a better measure of body composition than weight or BMI, it’s still not the best measure because, like weight and BMI, it wraps everything up into a single number.
Body fat percentage is actually just the ratio of your fat to your weight, which means it's affected by your non-fat mass as well as your fat.
The DEXA scans of the two men below show they have exactly the same body fat percentage - 21.6% - but very different body compositions.
Can you see now why BF% is not the best metric?
A DEXA scan measures your fat and lean tissue separately and gives you meaningful indices for each, most importantly your fat mass index (FMI) and your lean mass index (LMI). These two numbers tell you respectively how much fat and lean mass you carry in relation to your height. Crucially, your FMI is unaffected by muscle and your LMI is unaffected by fat. Unlike your body fat percentage, which is affected by both.
If we look at the FMI and LMI for our two male subjects, we see what polar opposites they are. For fat, one man is in the lowest 30%, the other is in the highest 35%. For lean mass and muscle the situation is reversed. In relation to his height, one man has more muscle than 90% of men, the other has less muscle than 90%.
Until you know your FMI and LMI and get a clear picture of your body composition you can't be really sure what your training and nutrition priorities should be.
Just before Christmas 2016 a Bodyscan client presented with the most dramatic change in body re-composition we have ever seen.
In just four months (from August to December), the client lost 11.5kg of fat and gained 6.4kg of muscle.
The numbers are impressive enough on their own, but are even more remarkable when you learn the client:
1. used no drugs, stimulants, supplements or shakes
2. was in a calorie deficit of about 500 calories a day
3. did zero cardio
4. is female
Prepare to forget everything you thought you knew about fat loss, muscle gain and bodybuilding when you read Joanna’s story. It starts with a Bodyscan DEXA scan that was “so mortifying, so shocking that it messed with my head and took me six months to recover from”.
Then in August last year, Joanna began a programme of Bayesian Bodybuilding. Click 'Read more' to continue.
We recommend most clients return for a follow-up scan three months (12-14 weeks) after their first to track their changing body composition.
It is quicker to lose fat than build muscle, so if fat-loss is your priority you should certainly look to return after 12 weeks and check you’re making sufficient progress.
If your re-scan results are good, it will give you reassurance that your training and nutrition programme is right for you and you can continue with more of the same.
Unfortunately for many, re-scan results are a disappointment. But knowledge is power, and you’ll now be able to make adjustments or stop and change course completely. Imagine waiting nine months or a year before you discovered you’ve been wasting all that time.
Typically, disappointment is due to high levels of muscle loss during a fat-loss phase (we regularly see people losing more muscle than fat) and, conversely, big increases in fat with little to show in terms of lean gains.
Uneven muscle gain where certain areas of the body progress faster than others is also common, as is not gaining any muscle at all. This can be due to a number of factors such as a too-low calorie intake (no muscle gain) or the incorrect training programme, intensity or rep range.
It is better to find out now that the desired changes in body composition are not occurring and do something about it.
Another reason for checking-in sooner is to be sure that the direction of travel has been consistent over the entire period. If you have more body fat in January than in the previous June, we’ll never know if it was just Christmas to blame or you wasted seven months doing the wrong thing. A re-scan in September would have provided some insight.
Finally, the constant refrain we hear from new clients is, “I wish I’d done this three months ago so I could see how things have changed.”
Only a DEXA body scan will give you the accurate, consistent, reproducible results that will enable you to optimise your progress.
If you’ve lost some momentum or are just not sure if you’re on the right track, booking a re-scan to see your results will be the motivation you need to kick start your body composition transformation.
We see many clients at Bodyscan who lose a lot of fat but who also lose a great deal of muscle too.
Sometimes so much that their body fat percentage actually goes up.
Look at the Bodyscan reports of these two clients who both did ‘biggest loser’-style diets with severely restricted calories: Nikhil, whose results are above, lost 4.7kg of muscle to his 4.9kg of fat, while Robert lost a whopping 10.8kg of muscle for 25.2kg of fat. Those big muscle losses do not bode well for keeping the fat off.
Indeed, loss of muscle is the reason why so many people who shed a lot of weight (see this article about DEXA and Oprah Winfrey) yo-yo back up again, and it highlights the importance of retaining your muscle mass when you embark on a fat loss regime.
Many people assume that when in a calorie deficit your body will turn first to its fat stores to make up the gap. But your body’s survival instinct takes an opposite view. Carrying muscle mass is calorie inefficient; big muscles burn a lot of calories even at rest. That’s why gaining muscle mass takes a lot of time, effort, heavy weights and loads of food.
Fat, on the other hand, is a great store of energy and helped ensure our ancestors’ survival when food was sparse and before there was convenience food within arm’s reach.
The need to survive and the expensive energy requirement of lean body mass is why your body quickly depletes your muscles - rather than your fat - when you reduce your calorie intake. The double whammy is that with lower muscle mass your body then burns fewer calories when at rest, so if you break your diet and simply go back to what you were eating before there’s now a bigger gap than there used to be between the calories you’re taking in and the calories you’re burning. Result - ballooning fat.
The statistics vary but a quick flick through a number of articles puts the number of people returning to their starting weight or above after a diet anywhere between two-thirds and 97%.
To retain your calorie-burning muscle, therefore, it’s a very good idea to add weight training to your programme. Unlike our big muscle-losers above, these two Bodyscan clients made resistance work a core part of their programmes: You can see from their Bodyscan reports that Katy reversed a fat gain/muscle loss to put on 3.2kg of muscle while losing 2.7kg of fat, and Rupert lost an incredible 14.3kg of fat while still building 2.2kg of muscle. The results speak for themselves.
In my experience as a personal trainer, success is wholly dependent on consistency. There is no point in any diet or exercise programme if you’re not going to stick to it, which is another reason why slashing calories and manic fitness schedules don’t work. In a couple of weeks you’ll be fed up and succumb to temptation. It's better to plan for slower, more gradual fat loss by restricting calories just 10% or 20% below maintenance levels and an achievable exercise and gym schedule. (Note: if you're gaining fat, you're already eating above your maintenance calories. Check out our body composition calculator for an idea of your calorie requirement.)
If your programme has derailed, it’s probably time to get a new Bodyscan baseline. We’ll give you achievable targets and then measure your progress in 3-4 months’ time.
Author - Archie Williams
This month (September 2016) we released the latest updated Bodyscan percentile tables, with data from over 2000 client scans - 1400 men and 650 women.
The new tables now includes regional fat mass, so you can see how typical your fat distribution is. You’ve been able to assess your muscle distribution with the previous tables, as described in this blog post about skipping leg day.
A ’typical’ fat distribution would expect to see fat mass for arms, legs and trunk in a straight horizontal line across the last three columns of the Regional Fat Percentiles table. The table is shown below.
The woman whose scan image appears at the top of this post might look to be carrying all the fat in her legs and trunk but when we plot her fat mass in the tables (shown in the report excerpt next to the image to be about 1.8kg in the arms, 10kg in the trunk and 5.9kg in the legs), we see that she actually carries proportionately most in the arms and least in the trunk.
Of course, you can’t spot-lose fat, but a change in the shape or angle of your plotted line through arms, trunk and leg fat mass will clearly show you how and where fat is shifting.
The data has changed little since March but the big sample size now gives us a very solid, reliable base against which to compare your individual results.
As well as showing fat and lean mass variations between the left and right sides of your body, Bodyscan can show you top-to-bottom variations too.
Using Bodyscan’s percentile tables, you can plot the lean mass in your arms, legs and trunk to spot discrepancies or weaknesses in your muscle distribution.
The most common variation we see is among gym-going men who commit that most heinous of crimes - skipping leg day. Take a look at this guy’s regional results and how they reveal workouts focused on arms and upper body.
The lean mass in his arms (the first two numbers) averages at around 5kg, in his trunk (the third number) at about 33kg, and about 10.8kg in each leg (the fourth and fifth numbers).
When we plot those quantities on our percentile tables (above), we see they equate to approximately these percentiles:
Arms (5kg) 95th percentile; Trunk (33kg) 77th percentile; Legs (10.8kg) 55th percentile.
That is, the lean mass and muscle in his legs is way behind that of his arms and trunk and, in absolute terms, just above average (the 55th percentile).
With a more even distribution we would expect similar percentiles across all regions of the body. To bring his legs into line with his arms, therefore, he needs to increase muscle mass in each leg from 10.8kg to about 13kg - a shortfall of more than 2kg in each leg.
So don't skip leg day!
On Tuesday 12th April, my first client of the day produced an incredible result.
In just four months Martin has lost 13.6kg (that’s over 2 stone) of pure fat. And he did it on a ketogenic diet, in which 70% of his calories come from fat, 25% from protein and almost none from carbs.
The fat loss would probably have been greater a month ago as recent family events forced Martin to diverge from the high-fat, ultra-low-carb regimen.
The highlights of his report are:
Martin’s results endorse the groundswell of opinion and evidence that it’s OK – in fact, highly beneficial – to eat plenty of naturally occurring fat and that carbohydrates are the underlying cause of obesity.
If you’re interested in Martin's information sources, he kindly points to:
We also found this very interesting 30-minute ‘Catalyst’ programme from ABC Australia, made in 2014.
Since November, Martin has consumed his high-fat diet in a time-restricted window (a version of intermittent fasting) between noon and 8pm, and also aimed to be in a calorie deficit of 30-50%. Some keto advice is that you don’t have to count calories because your hunger levels are very well regulated without carb-induced insulin spikes, but Martin says keeping a sharp eye on calories was crucial because of the high-energy value of high-fat foods – a few macadamia nuts can cause a calorie blowout.
In February, after five months of strict ‘keto’ (he began the keto journey last September), Martin moved to having a carb re-feed once or twice a week, usually the night before bodyweight circuit training (TRX, press-ups, squats and lunges). This ‘cyclical keto’ with heavy-duty carb-ups of between a few hours and two days is outlined in ‘The Best Ever Bodybuilding Diet?’. Martin’s carb content would rise to 50% in these periods.
His more than 5:1 ratio of fat-to-lean loss is excellent by any standard (especially considering the sheer amount of fat he shed) and one wonders if he would have maintained more or even all his lean mass with a lower calorie restriction and by increasing weights beyond body weight.
Martin’s lifestyle changes started last August, when he was 131.5kg (21 stone) and wore XXL shirts and 44-inch trousers. He quit smoking and sugar and began restricting carbs and calories. In September he followed the keto rules more closely and saw improved results. He then replaced breakfast with a ‘bulletproof’ coffee (coffee and coconut oil) before removing the calorie-rich oil to start the 16:8 intermittent fasting.
He’s now a medium, 32-inch waist and below 90kg for the first time since he was 12 years old. Inspiring stuff.
Martin’s says: “It's hard to start, like any diet, but the difficulty is in establishing new habits. The biggest one is losing the starch component of most of your meals – it's culturally ingrained.
“Once you're used to it, it's quite easy. Keto is challenging in that it's a binary proposition – like being pregnant, you're in a ketogenic state or you're not. So you can't cheat (except in very controlled circumstances with strategic carb re-feeds).
“Get enough salts when you start, watch your fibre intake and expect to take a few weeks for your body to adapt. Once it does there are many benefits. For me, fat loss obviously, but also the steady blood sugar, reduced hunger and mental clarity are great side benefits.”
We hope you find Martin's story interesting.
MAN v FAT published one of the very first reviews of Bodyscan when we opened in London in January 2015. Today, the 35,000+ member men's forum is the biggest online referrer of hits to the Bodyscan site after Google Search.
It makes perfect sense, then, for us to team up with MAN v FAT and offer a free DEXA body scan plus face-to-face consultation in our latest competition. We're kicking ourselves we didn't think of it earlier!
You don't have to be a bloke to win, so click this link to go to the MAN v FAT website and enter now. You can ratchet up your entries by getting your friends to enter too.
You'll get the most accurate and precise measurement of your body fat and lean mass, plus data about your visceral fat and bone density too. Plus we'll take you through your report in detail and help you set targets (in kilograms) for fat loss and muscle gain.
The Bodyscan website and, more importantly, the booking pages that ask for your personal information and credit card details are now SSL-secure.
That means all data passed between your browser and the booking engine web server are encrypted and remain private. You can see this marked by the HTTPS (rather than just HTTP) at the front of each page's URL in your web browser.
Due to some software restrictions, we've had to take the booking engine (made by Australian company Bookeo) out of Bodyscan's own website and host it on its native site. It's exactly the same engine and works in exactly the same way but is no longer embedded as a widget on the Bodyscan booking page.
The upshot is that when you book a Bodyscan DEXA body fat test you can be sure your personal and credit card details are completely safe.
If you've been to Bodyscan for a DEXA scan then you can use the Bodyscan body composition calculator to set targets for fat loss, muscle gain or both.
After entering the data (in kilograms, not grams) from your DEXA Bodyscan report on the first (RMR) page (which gives you two formulae's outputs for your resting calorie requirement), you can advance to the Body Composition Calculator, which allows you to set targets for fat and lean mass, using your FMI and LMI.
As I say in another blog post, these indices are the best numbers to use because FMI is not affected by muscle and LMI is not affected by fat.
To arrive at FMI and LMI targets, you might want to use the Bodyscan aggregate data tables that are available here. You can see from the blue (male) tables, that the median (50th percentile) score for male FMI is 5.78 and the median LMI is 19.3. The orange (female) tables show medians of 7.45 and 15.6 respectively. (These figures have been updated as of September 2016).
If you're already carrying more fat and/or less lean mass than the average Bodyscan client, you might want to use these median values as your target FMI and LMI.
On the body comp calculator you can move the fat and lean slidebars until your FMI and LMI (on the left of the page) reach or come close to those targets. You'll then have (immediately above the slidebars) the absolute amounts, in kilograms, of fat and muscle you need to lose/gain. You'll also see your projected change in weight - which might even be zero.
If you're better than the Bodyscan client average, you can set your targets to be the top quartile or top 10% or better.
The FMI and LMI targets come with a caveat - the aggregate Bodyscan client data do not represent random samples of the UK population; they are the results of people who have chosen and paid to have a DEXA scan. Also, the tables are not age-matched and they contain a range of ethnicities. Nevertheless, they are a good starting point to set a tangible, achieveable target.
Whilst lean mass does decline in later years, it is not by much, and this decline only affects LMI and therefore body fat percentage. It does not affect fat mass or, therefore, your FMI.
Easy? Now all you have to do is achieve your target!