To Be Determined Journal

To Be Determined is a journal of cycling, adventure and photography, curated by a NYC-based cycling team known as TBD Racing or Team TBD. From criteriums to cyclocross to product reviews and travel diaries, it is all part of the TBD Journal.

Energy Balance

2014 is underway. By this time, competitive cyclists have started to fill in their race calendar, getting ready for this season's racing. They (or their coaches) have spent hours framing a training plan that optimizes performance to fit the racing calendar. But, what about your nutritional plan? Nutrition is a huge industry with an enormous amount of information, claims, theories and fads. It is overwhelming and full of contradictions and marketing, which can sometimes lead people down the wrong path, confuse people and end up doing more harm than good. I believe in keeping it simple. What follows is a rough guide to give you the framework to start thinking about how your training and your nutrition can work together.

Think of nutrition as fuel. Your body uses nutrients as fuel for physical and mental performance. Change in Body Stores = Energy in - Energy out. Essentially, if you match energy in with energy out, your change in body stores (fat, muscle, etc.) remains the same. Play with either side of the equation and you can increase or decrease these body stores (gain weight or lose weight). Obviously this is a simplified view of energy. There are numerous factors which can alter the equation, but for reasons of practicality, I choose to ignore the more minute factors.

Shedding some pounds is beneficial to cyclists looking to up their power to weight ratio (expressed as watts per kilo). To put some numbers to it, a cyclist putting out 300 watts at 165 pounds will achieve the same watt to kilo ratio by losing 5 pounds as he would gaining 10 watts. Gaining 10 watts is no small feat. Shedding 5 pounds through some basic adjustment to your diet may be an easier task. The tricky part is figuring out how to balance your training load with your diet in order to ensure maximum performance without excess calories adding unnecessary weight.

Instead of just guessing at it, let's get back to the energy formula. This equation is a great way to shed some light on your energy balance and how it relates to your training load. For the purpose of example, I will use my own stats to estimate a day's energy expenditure.

Change in Body Stores = Energy in - Energy out

First, I'll focus on “energy out”. In the most basic terms, energy out is comprised by:

  1. BMR (basal metabolic rate)
  2. TEA (thermic effect of activity)
  3. TEF (thermal effect of food)

This may sound complicated, but it's really not, and I'll break it down to show you.


Basically your BMR is the amount of calories your body uses to keep you alive at rest. This includes keeping your heart beating and your lungs taking in and expelling air. Although there are individual variations in BMR, we can use an equation to get us close. The equation looks like this:

BMR = 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) - ( 6.8 x age in years ).

Plugging in my stats (69 kg, 180cm and 28 years) I get a BMR of 1720.9 calories.


The next element to take into consideration is the most variable – the thermic effect of activity or TEA. For cyclists, the overwhelming majority of this energy expenditure is from training although it may be important to some people with higher levels of activity from work or commuting etc. to add these factors into your energy expenditure. For this example, I will only use the energy expenditure from cycling. To be specific, the energy expenditure from cycling depends on many variables – duration, speed, temperature, body composition, weather, terrain etc. Essentially, calculating this can get pretty complicated. Fortunately though, we have some help. For the modern cyclist training with power or heart rate, this is an easy number to find – your cycling computer should be able to tell you your energy expenditure in kilojoules and/or calories. If you are lucky enough to be using Sixcycle, your kilojoules and calories are shown for each workout. Check out the Sixcycle ride file below by clicking the summary image.



This will give you a relatively accurate assessment of the energy demands of a particular ride. If you are without a tool like Sixcycle, a rough estimate can also be calculated at various websites. The online calculator here accepts a lot of variables and is a good tool, but you can increase the accuracy of this calculation with access to a more direct measurement of caloric expenditure using your power meter and/or heart rate monitor and program like Sixcycle . The ride shown above was a longer one. Sixcycle tells me that I burned 3453 calories and went about 80 miles.


So now I have my basal metabolic rate (1720.9 calories) and using the example above, the thermal effect of activity (3453 calories). Now we can add the third element – the thermal effect of food. This is a flat 10% of your BMR and TEA. It accounts for the energy that is needed for your body to digest, absorb and distribute food energy. 10% of BMR + TEA is 517.39 calories. This gives me a total of 5,691 calories burned on this specific day. Now, I have an idea of how to adjust my calories in order to gain, lose or maintain body mass.

This gives you a good framework for the quantity of food you need. How you get those calories also matters. Generally, endurance athletes need 1.2-1.4 grams of protein and 5-10 grams of carbohydrates per kilogram of bodyweight. For lighter training days stay to the low side of those ranges and for harder blocks of training push those ratios up to the top of the range. Since carbohydrates are the main source of fuel for endurance cyclists, it is also important to stay ahead of your training. The day before a race you may even want to consume 12 grams of carbohydrates per kilogram. This will top off your body's stored carbohydrates (called glycogen), essentially like filling the fuel tanks before the race. So on this particular day I would use the top end of the ranges and aim for about 97 grams of protein (69kg x 1.4) and 690 grams of carbohydrates (69kg x 10) in order to refuel and give my body the macronutrients it needs to rebuild and be ready for the next training session.

To review....

  1. Calculate your BMR  with 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) - ( 6.8 x age in years )
  2. Measure or calculate your TEA with your cycling computer, training software or an online calculator.
  3. Add BMR and TEA and then add 10% of that total to account for TEF (thermic effect of food)

The crucial point to take away from is that your energy demands vary greatly day by day. To dismiss this would be to ignore one side of the energy balance equation and tip the scales one way or the other. So give some thought to lining up a nutritional plan with your training plan. As you progress through your periodized training plan, your energy expenditure ebbs and flows. Start by tracking your training week. This will give you a basic idea of where you are burning your calories and where you may need to adjust your intake. From there you can start with a 7 day day plan that fits the phase of training you are in. As you progress into the season, and your training changes in intensity or duration, adjust for any changes, accounting for race weeks, taper weeks and rest weeks. By calculating intake vs. output for a week you will be able to see how balanced your current plan is. Does it align with your goals? It may now be clear why it has been difficult to drop those last couple pounds of winter weight.