Intuitively, it makes sense to eat more food on days you’re training hard vs. days when you’re not training or have sessions that require less energy.
The idea is that you want to provide the body with more fuel for the sessions that need it most.
This is sometimes referred to as ‘calorie-cycling’ or ‘calorie-undulating’.
If you’re someone who is trying to lose body fat, you’ll probably recognise an issue here, and may find yourself asking, “If I increase my calorie intake on each training day, will that get in the way of my fat loss goal?”
Well, if you were to simply increase your intake on training days and not make up for this by decreasing your intake elsewhere, the answer would likely be yes.
However, if you were to make up for the increase on training days by decreasing your intake on non-training days, you’d be able to have more fuel in your body on the days it’s needed most, whilst still maintaining your daily average calorie intake.
As a result, you’d be able to achieve the same fat-loss progress as you would had you kept your intake constant across all days, whilst performing at a higher level.
Defining Your Days
When implementing an approach like this, it’s important to define your days.
If you’re a field sport athlete (GAA, hurling, rugby, soccer, etc.) you can consider ‘training days’ as those days when you’re training intensely and for longer durations, e.g. with a team or doing tough running/cardio-based sessions alone.
You can then count non-training days as those days where you’re not training at all, or those days where you’re doing gym sessions or other similar sessions that, while tough, aren’t going to demand the same energy requirements as those of longer running sessions.
On the flip-side, if you consider strength or muscle gain your main goal, the days you’re in the gym can become your training days, and the days you’re not training in the gym can be considered non-training days.
In exceptional circumstances, you could have 3 different daily intakes (low, medium, and high), but this would be excessive in most cases, without much benefit, so ‘training days’ and ‘non-training days’ is sufficient for most athletes to reap the benefits of this approach.
Should You Use This Approach?
So, should you implement this approach?
The first thing to consider here is the concept of ‘consistency over perfection’.
Specifically, even if you agree that a calorie-cycling approach is technically better, if implementing it leads to you being overwhelmed and inconsistent, a simpler approach of hitting a consistent calorie target, regardless of each day’s training level, is likely to lead to better outcomes.
If in doubt, start with a period of a few weeks where you’re keeping calories constant every day, before moving to this calorie-cycling approach once you’ve built up some consistency.
Another factor that matters when it comes to deciding if this approach is suitable for you is your current body composition goal.
Someone who is in a fat-loss phase is likely to benefit most from calorie-cycling, since it will allow them to be close to a maintenance level of calories on training days (providing adequate calorie intake for the work required), whilst being in a larger calorie deficit on days where they aren’t training, allowing them to see fat-loss over time as a result.
Someone who is currently eating at a maintenance level (where body weight is staying stable across weeks on average), is also likely to benefit, since they will be able to stay at the same weight, whilst having extra calories for fuel on training days.
Someone who is currently eating at a level that has them purposely gaining weight (i.e. they’re eating in a calorie surplus) is not likely to benefit much from this approach, since they’re already eating excess calories that can be used as fuel, both on training and non-training days.
How Much Extra Should You Eat?
Again, there are numerous factors at play here, such as how low your calorie intake currently is and if you’re currently experiencing hunger on a regular basis (since bringing calories even lower on numerous days per week is likely to increase hunger levels).
I’ve found from experience working with athletes, that around a 10% increase on training days tends to be a solid approach.
This figure is by no means fixed in stone, but is based on experience with athletes as well as what logically and logistically makes sense.
Logically, an extremely small difference of say 2% would be unlikely to make any difference in terms of the effects you’re hoping for, and a much larger amount like 25%, for example, would likely lead to excessively low intakes on non-training days.
Increasing your calorie intake on training days by 10% means that if your current daily intake (calculated in previous articles) was 2500 kcal, that would increase to 2750 kcal (2500 + (10% of 2500)) on training days.
You could simply leave it at that, increasing your intake on training days, and leaving your intake at the regular level on non-training days, but that will lead to an overall increase in your daily average calorie intake across the week.
If, however, you wanted to maintain your average daily calorie target for the week, then you need to adjust your non-training day intake downwards in order to even out the average.
If you are training 3 days per week, and therefore eating that new 2750 kcal target 3 days per week, you’ve just added in an extra 750 kcal (250 x 3) to your weekly calorie intake.
In order to ensure your average daily intake for the week remains the same as it was before, you then need to take that extra 750 kcal out of the other 4 days of the week.
That can be done by simply dividing that extra 750 kcal by 4, since there are 4 non-training days: (750 / 4 =187.5 - Call it 190 kcal for ease of maths and practicality), leaving your non-training day intake at about 2310 kcal (2500 - 190) and training day intake at 2750 kcal.
(Note: Don’t worry if that was confusing. There’s a super simple calculation at the end of the article).
Of course, your calorie intake will likely be different than the 2500 kcal in the example above, and you may want to experiment with increasing or decreasing that 10% figure, but hopefully the maths example shows you how you can match it to your needs and goals.
Adjusting Your Macronutrients
In general, any changes in calorie intake on training vs. non-training days should be reflected in carbohydrate intake as opposed to protein or fat (this is why sometimes this approach is called ‘carb-cycling’ rather than ‘calorie-cycling’).
The reason for this is that the body’s protein requirements generally stay the same on a day-to-day basis, as does fat, and recommendations for both of these are generally based on your body weight, whereas the body’s carbohydrate requirements generally change based on your energy output demands.
It also logically makes sense that since carbohydrates are the main energy source used in high-intensity training, you would adjust your intake of them based on the level of high-intensity training you were doing.
There may be exceptions to this, where fat or protein will be also adjusted slightly.
An example of this would be where calorie intake has become so high that it becomes too difficult to get all the extra calories from carbohydrates alone, and increasing fat as well might be a good option.
As a final note, many athletes have achieved their body composition and performance goals whilst keeping their calorie intake consistent through the week, without the need to change for training vs. non-training days, so consider the calorie-cycling approach as an optional extra, if and when it is implementable on a consistent basis for you, and when you’ve already built up consistency in the basics.
Article Written By Conor O’Neill
Conor O’Neill is a Nutritionist, Strength & Conditioning coach, Psychologist, and Author.
He has helped 1000+ everyday athletes to pursue excellence in their physique and performance through optimising their nutrition, training, and psychology.
You can find out more about The Everyday Athlete Program by going to everydayathleteprogram.com/coaching.