How fat is really fat?

Regular readers will know about my “Fit at 40” challenge and I have to say it’s pretty hard work right now. I lost the first stone (and a bit) and I built up to the point where I ran my first 10K race (albeit a little slower than I would like) but now it’s into the real hard slog… and I’ve found that I need to focus a little harder (although I’m still heading in the right direction).

I mentioned previously how my friend and former colleague, Garry Martin, is providing motivation with a sponsorship deal that requires me to meet certain targets that we have agreed as realistic but challenging. I will lose the three-and-a-bit stone, and I will run three races of at least 10K before my 40th birthday – but I really do hope to do a little better than that (let’s call it a stretch target!)

Friends and family keep on telling me that I’m looking slimmer, fitter, and healthier, but I put that down to wearing dark colours, a recent holiday leaving me suntanned and breathing in/standing upright! The fact is that the scales tell me I’m not shifting the weight fast enough – and the running is getting harder, not easier. Even so, I decided to take a look at my body fat measurements.

It seems that, in the UK, health professionals are obsessed with the Body Mass Index (BMI) – a simple calculation based on height and weight.  That’s all well and good, but some of us really are “stockier” than others.  According to a simple BMI calculation, I am obese (I am) but, I’ll still be overweight when I reach my goal… in fact, I’d need to get below 12 and a half stone to be “healthy”, despite having not been that weight since I was a teenager (and still growing up, rather than out).

In theory, all of this exercise is helping me to build muscle so it makes more sense to understand just how much of me is fat.  For a while, I was using one of the many calculations available on the ‘net but they really do vary tremendously. So much so that they can only be considered as a guide (not much better than the BMI):

More importantly, the calculation I was using wasn’t suggesting any progress – despite clearly losing weight and being a lot leaner, my wrist and forearm measurements (two of the metrics used) are probably not going to change much.

When I look at my “ideal weight” there are just any many ideas of “ideal”:

  • Based on the Robinson formula (1983), my ideal weight is 156.5 lbs.
  • Based on the Miller formula (1983), my ideal weight is 155.0 lbs.
  • Based on the Devine formula (1974), my ideal weight is 160.9 lbs.
  • Based on the Hamwi formula (1964), my ideal weight is 165.3 lbs.
  • Based on the healthy BMI recommendation, my recommended weight is 128.9 lbs – 174.2 lbs.

Then, last month, I saw that one of the local leisure centres was advertising Body Stat tests (body composition testing) for £5, so I booked myself in.  Using a bio-electrical impedance analysis (BIA) test I was given a range of figures indicating how fat I am and what I should be aiming for. BIA is not without it’s faults but at least by using a commercial product rather than a consumer body fat meter I’ll have increased the chances of accuracy. Just as important was the confirmation that my goal weight is realistic as well as the information that I’m not sufficiently hydrated (drinking more water should help me to lose weight). It also told me my basal metabolic rate (I could also calculate that myself or use a different calculation to take into account exercise and target weight loss), which explains why I’m so damned hungry if I don’t eat enough… and I want to lose weight at a sensible rate or 1-2 pounds a week, not go on a crash diet (I use the Weight Loss Resources site to help with tracking my food and exercise).

Ideally, I would have baselined this when I started the challenge but at least I have the numbers now I’m part way in, and I can check them again as I hit my milestones over the coming months. For what it’s worth, the ideal weight that the Body Stat test came up with was 85-91kg (13st 5lb-14st 5lb) and 13-19% body fat. That seems a lot more realistic than the numbers above and the top end is just below my “Fit at 40” target (so, “Fitter at 41?”)

Just on more thing before I sign off… a quick video from the Dads’ Race at my son’s school sports day last week:

I think I came second (I’m in the green t-shirt). The challenge continues…

3 thoughts on “How fat is really fat?


  1. I feel your pain!

    After my knee operation I figured I’d put on about a stone and wanted to lose this ahead of the new football season but I was so focussed on just getting the knee back in working order I hadn’t really thought about doing anything about the weight.

    Some twitter friends pointed me to myfitnesspal.com and I’ve been tracking the food that I eat and the exercise I do and have so far lost 2lbs a week (currently 11lb lost)

    While it was all new and the first 5-6lbs fell off it was easy to stick to the program – now I’ve been doing it for 40+ days it’s become the same slog you mentioned.

    I’ve still got the target of being fit for the football season motivating me at the moment

    Like any self respecting geek, as you’ve already done I’ve ready more about BMR/BMI/VO2MAX/ETC than i ever thought I’d be interested in :-)

    Keep at it!


  2. Cheers Andy – I actually wrote this a few weeks ago, since I wrote it thinks have picked up – got over the “hump” and losing weight at 1-2lb a week, plus ran 5 miles today and it felt pretty good again… I’m not letting this one go! (and good luck with yours too – hope the knee is recovering well). Mark

Leave a Reply