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THE LAUNCH – Individualised Metabolic Nutrition

Food For Sport is launching a new service in Cape Town using state of the art technology to assess and better adapt your nutrition and exercise programme to suit you as an individual. These tests are available as part of complete nutrition and exercise planning packages or as stand-alone tests. This means you, your trainer or dietician may use them to assess your metabolic function and adapt your programme or plan accordingly.


With the use of a metabolic cart the gases that you breathe are analysed during rest or exercise. From this data we can evaluate energy expenditure and substrate utilization (fat vs carbs) as well as standard measures of fitness and various thresholds.

We produce energy for our body to function from fat and carbohydrate reserves or foods containing these. There are other energy production pathways which are used for very short duration exercise and under stress or disease states which are less relevant here.

The Resting Test

This test allows us to determine your resting metabolic rate and respiratory exchange ratio, two valuable elements in designing and monitoring nutrition or exercise programmes.

The total amount of energy we expend every day is made up of four components:

  • Energy used for basic body functions at rest (sitting or lying down) is called resting metabolic rate
  • Energy used for daily activity, small movements and fidgeting is called non-exercise activity thermogenesis
  • Energy used for structured exercise is called exercise activity thermogenesis
  • Energy used to digest and metabolise the food that we eat is called the thermic effect of food

Resting metabolic rate (RMR) makes up the largest component of energy expenditure unless we are taking part in very long exercise sessions. In determining your nutritional requirements it is extremely useful to know your metabolic rate. Your age, fitness level and amount of muscle you have are some of the factors that influence metabolic rate but so do various hormones as well as nutritional status (READ HERE FOR MORE). When determining nutritional needs from RMR we generally use an equation that estimates your rate based on some of these factors. But there is a large inter-individual variance in metabolic rate from the means and averages that these equations are based on. This means your requirements estimated through an equation might be off from your actual needs which would impact the success of a weight loss or weight gain plan.

Respiratory exchange ratio (RER) is simply a ratio between how much oxygen you are breathing in against the amount of carbon dioxide you are breathing out. Without discussing cellular processes this ratio allows us to estimate respiratory quotient (RQ) at rest, or how much fat and how much carbohydrate is being used to produce energy. A value of 0.7 suggests 100% fat utilization where a value of 1.0 suggests 100% carbohydrate use. The crossover point where energy is being provided by fat and carbohydrate in equal quantities is 0.85. This is great information for use during rest and exercise. At rest we should be using more fat than carbohydrate but a poor diet or low fitness levels (amongst a few other things) may result in using more carbohydrate. Ideally we want to be flexible enough to use fat when we should (rest and low intensity exercise) and be able to switch to using carbohydrate when we should (after a meal and during high intensity exercise).

Using carbohydrate in a fasted state and at rest is an introduction to poor metabolic flexibility and may lead to difficulty losing body fat. In addition developing areas of research suggest that there may be links to chronic diseases (eg. diabetes), inflammatory conditions and even cognitive decline. “Carbohydrate burners” generally respond well to controlling their intake of macronutrients proportionally (fat/carbohydrate/protein), timing their meals and a few other tips and tricks to improve their use of fat. Athletes could also benefit as body composition control becomes easier and reliance on regular eating during exercise is reduced. “Fat burners” generally get away with eating a greater variety of foods and fat loss goals should be achieved through simple calorie restriction.

Monitoring weight loss also becomes easier with RQ as we should get an indication of whether your body is moving toward a greater use of fat and obviously weight loss is only successful if we are losing fat and not muscle or bone. This can be confirmed with body composition monitoring too. Similarly monitoring changes in metabolic rate and flexibility can allow us to fine tune and adapt a nutrition and exercise plan to achieve sustainable results.

Who would benefit from this assessment

  • Anyone looking to lose fat
  • Those who are struggling to lose weight despite various attempts
  • Yo-yo dieters
  • Those prone to storing weight around the waist
  • Those who are interested in low carbohydrate diets
  • Anyone with metabolic disturbances such as glucose intolerance or diabetes

An example of the test data can be seen here. This demo shows an individual with a slightly depressed metabolic rate relying a little too heavily on carbohydrate as a fuel during rest.

Screenshot 2014-11-25 12.16.01

The Exercise Tests

A variety of exercise tests and protocols are possible with different applications depending on what information is required. Generally sub-maximal testing on a treadmill or cycle ergometer will be performed. A metabolic fitness test to assess training zones and heart rates that elicit different carbohydrate and fat utilization rates provide a valuable tool for individualising nutrition and training recommendations. Using the respiratory exchange ratio (see above) the workloads where maximal fat oxidation occurs can be evaluated and incorporated into training programmes. Assessing the crossover point allows metabolic efficiency to be assessed to further work on nutrition and exercise strategies that encourage greater utilization of fat as a fuel for exercise. This has potential benefit for body composition control as well as athletes who struggle with GI issues (cramping, diarrhea, bloating etc.) during exercise. Training the body to use fat at higher exercise intensities also saves valuable glycogen for when it is needed most – high intensity efforts, making a break or climbing a hill for example. The aim is to find a balance, the sweet spot, of switching between fuels effectively without compromising performance.

Substrate utilization tests are assessments of real-life situations. A substrate test would involve running or cycling at speeds or intensities similar to those which are expected during a race or event. From this re-fuelling strategies can be implemented with guidance of how much and how often you should be eating or drinking. The energy cost of typical exercise routines or sessions can also be quantified.

Measurement of standard markers of fitness and exercise capacity are also possible which include VO2 max, anaerobic threshold or exercise economy.

The metabolic cart used to assess these different elements is not limited to use in the lab which adds exciting potential. This allows real-life assessment of training or exercise sessions to be conducted and energy expenditure and substrate utilization to be monitored. This provides the opportunity of learning how your workout fits in with your goals or monitoring progress of a standardised session.

The example below is the data from an exercise test showing:

  • A decent level of fitness

Screenshot 2014-11-25 12.40.47

  • Where I have highlighted the training zone that will maximise fat utilization

Screenshot 2014-11-25 12.37.55

  • And the training zones and energy expenditure that would be used to individualise a programme

Screenshot 2014-11-25 12.41.26

I am excited by these developments and the potential to better assess each individual and provide useful information that will hopefully better serve them to reach their performance or health related goals. Have a look at the services page for more information or get in touch with any questions or to book your assessment.

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