Establishing baselines is essential for knowing where you are heading and for supporting the process of making positive changes. To establish your goals and what you will do to achieve them, first understand where you are starting. Not only does this create reality, but it also helps you know what is required to make the change in a systematic, structured manner.
ASSESSMENT
Assessing body composition is not about getting ripped, let's get this clear. Body composition is associated with a myriad of disease processes, including diabetes, heart disease, cancer, osteoporosis, sarcopenia and metabolic syndrome. From a performance perspective, improving body composition can be an effective way to enhance power-to-weight ratios, which will be essential for performance on the bike and during the run. When assessing body composition, it can be used to establish a baseline and objectively evaluate the effectiveness of a nutritional and/or exercise intervention. It monitors changes over time and can be an effective tool for adjusting and assessing what is required for an individual.
There are multiple ways in which to assess body composition. These include girth measurements, bioelectrical impedance, skinfolds, DEXA, and underwater weighing. These varied methods will have both pros and cons. These differing methods rely on differing models of body composition assessment.
WHICH TO CHOOSE?
Your budget will dictate the method and also your commitment to assessment .
A PIECE OF STRING
The first place to start would be simply a girth measurement. Take a piece of string and measure your height. Next, fold that same piece of string in half. Place it around the narrowest part of your waist, and the two ends should touch or overlap. Essentially, your narrowest aspect of your waist should be half your height (Waist to height ratio =/< 0.5). You can calculate your actual ratio by simply using the formula below:
Waist to height ratio = waist/height
You are aiming for a range of around 0.45-0.55. If it is under 0.45, you may be underweight and if you are over 0.55, you may be overweight. Both carry potential risks - being under could leave you open to osteopenia, osteoporosis or Relative Energy Deficit in Sport (REDS), whilst being over could leave you at risk of metabolic syndrome, Type II diabetes, heart disease and stroke. Other factors do contribute to the relative risk of these disease processes.
TAKE HOME: Super simple, quick and effective. This simple measurement may be the starting point for further investigation.
SKINFOLDS
If you are going to get a skinfold completed, find a practitioner who has completed the International Society for the Advancement of Kinanthropometry (ISAK 1). This will ensure that the assessment is thorough, consistent and reliable. The evaluation will likely be at seven sites and will take 15-30 minutes to complete. The practitioner will mark your body and perform the measurements twice to ensure accuracy and minimise measurement error. If an error does exist, then a third will be taken.
TAKE HOME: Choose an ISAK practitioner to ensure measurement accuracy. It should include at least seven sites and be repeated at least twice.
SIDE NOTE: Skinfolds do not relate to hormones, and any practitioner who explains your skinfolds do relate to cortisol, oestrogen or your thyroid should make you very wary of them.
BIOELECTRICAL IMPEDANCE ANALYSIS (BIA)
These are the machines you stand on —plus or minus —then grab a pair of handles. They will pass a current through your body and estimate your fat-free mass (FFM) and fat mass (FM). The principle is that lean muscle consists of water and electrolytes and acts a good conductor, whilst fat mass does not and is a poor conductor. There are many confounding factors related to BIA, including hydration status, nutritional status, menstrual cycle, and electrode placement. Bioelectrical impedance analysers use equations to describe statistical associations based on a specific population. As such, the equations are only helpful if you closely match the specific population in body size and shape. Significant improvements have been made with these machines, and now some use multiple frequencies and bioelectrical impedance spectroscopy (BIS) to assess total body water (TBW), even separating it into extracellular and intracellular water. Despite these improvements, the real use of BIA is to describe the average body composition of groups of individuals rather than to track individual changes, due to the often large measurement error.
TAKE HOME: FFM is often underestimated in normal weight individuals, whilst overestimated in obese individuals when compared to DEXA.
DUAL ENERGY X-RAY ABSORPTIOMETRY (DEXA)
This method will assess body fat (visceral and subcutaneous), muscle, and total body bone mineral density (TBBM). It is considered the gold standard for bone mineral density measurements, so if you are a female endurance athlete, this is certainly worth considering for your body composition assessment, as you get that bonus. This is a KEY reason to use a DEXA scan if you are a female endurance runner with a waist-to-height ratio </=0.5 and have had irregular eating episodes that have resulted in under-fueling your training and performance. For body composition, it is not 100% accurate, as none of the tests are, and it assumes constant hydration status, which could result in an error of 1-2% in body fat and lean tissue.
TAKE HOME: The DEXA is quick to use, safe and as reliable as you can get. Ensure you are hydrated before each use, standardise the time of day, and, if you are a female, aim to get it at the same time in your cycle.
IN THE END
No single method is the gold standard in body composition assessment (4). All have their advantages and disadvantages depending on cost, practicality and measurement error. Whichever you choose, consider standardising the method as best you can and stick with that choice for consistency. One other important consideration is that if your goal is improving body composition for performance purposes, be aware that maintaining a low percentage of fat over a long period of time is not only difficult yet also for a lot of people a lot of effort and can result in the increased risk of upper respiratory chest infections and other musculoskeletal injuries. Working alongside a professional practitioner to periodise your plan in order to hit targets when required would be sound advice to follow to ensure you are as healthy as you can be all year round—peak for your performance, in other words.
NUMBERS TO ASSIST THE PROCESS
Utilising a food diary (such as Fuelin) and tracking weight are practical ways to implement the nutritional intervention program (Fuelin) and monitor progress. Initially, it may take a little time to adjust your energy intake (food and drink) to achieve your goal. The reason is that an estimate of your energy intake is calculated using mathematical formulas, such as the Harris–Benedict or Ten-Haaf equation. By using these formulas, applying a structured nutrition & training program and tracking, you can make solid progress towards getting leaner, maintaining weight or getting bigger - whatever your goal is.
Cheers,
Scott