In our series so far, we’ve looked at structuring a weight loss phase from expected timescales, safe upper and lower limits of weekly rates of loss, as well as the most common barriers individuals meet in creating a successful outcome.
If you haven’t read our insights into Effective Body Composition Changes, Upper and Lower Limits of Weekly Fat Loss or Typical Timescales for Fat Loss, it may be worth taking a look through before taking on this weeks!
Today we’re going to deep-dive into the role of calories during fat loss phases, how we select a starting point for caloric intake and how we balance daily activity, exercise and food intake to optimise our outcomes.
Our first starting point is a simple questions, why do calories matter?
Well based on what we’ve learned so far, if we don’t create a calorie deficit it is incredibly unlikely that our bodies are willing to give up its own fat stores for energy usage. The body will always preferentially use the incoming excess energy from food, without it our species would have become extinct a long time ago.
As we have discussed in previous insights, the concept of body recomposition, in which we may potentially both gain muscle and lose body fat at the same time, is entirely possible with the very early beginning stages of resistance training or targeted nutrition.
However, in intermediate and advanced individuals that have been both training and dieting successfully over long periods of time, the results of targeted recomposition are underwhelming. The idea of building muscle (calorie surplus) and losing body fat (calorie deficit) are directly opposed. During recomposition in more advanced individuals, we see only small scale changes due to the lack of sufficient stimulus and resources to add further growth beyond what the body deems necessary.
Mechanistically, being in a hypocaloric state quite literally causes intracellular pathways to activate that enable fat loss to occur. It’s the fundamental starting point if we are looking to make a change in body fat levels.
When it comes to selecting a calorie target to begin our journey, many methods exist. We have tables, calculators and formulas that all can provide us a starting point, with each having individual pro’s and cons.
Online calculators are a simple way to gather some basic details to get going. They will often require you to input variables such as your age, gender, height, weight and potentially level of activity. From these calculations will be an estimation of total daily energy expenditure (TDEE). Overall, calculators are quick to use, easily accessible and don’t require too much effort for the user.
Calculators are however dependent on formulas to establish TDEE. Various formulas also exist, each taking into account slightly different variables for use with different populations. However the one we utilise at IFT is the Mifflin St Jeor estimation of basal metabolic rate, with an added activity factor to establish estimated TDEE.
If you feel like having a go at the math, the formula for both males and females is below!
Males: BMR = (10x weight in kg) + (6.25 x height in cm) – (5 x age on years) + 5
Females: BMR = (10x weight in kg) + (6.25 x height in cm) – (5 x age on years) – 161
We then take the estimation of BMR and add in our activity factor depending on the level of activity of the individual in question.
Sedentary or Light Activity – BMR x 1.53
Active or Moderately Active – BMR x 1.76
Vigorously Active – BMR x 2.25
This is our starting point for maintenance calorie. However, even when we factor in these formula components, we may still fall within one of the brackets of activity level as above, it doesn’t truly represent us as an individual. So within our category we may need to alter over time to find the actual value that maintains our bodyweight specific to us.
Simpler formulas also exist based on regressions of these equations above, the simplest of which is to take your bodyweight in lbs (kg x 2.2) x 10-12 depending on activity levels and resistance training volume.
The key to remember however is all tables, equations and calculators are merely a starting point only. They can each be off by between 500-1000kcals. It’s all individual.
To show just how much, we will use a typical client avatar and put them through each method.
- Female – 65kg – 30yrs – 5ft 7 – Sedentary Office Job – 25% Body Fat
- Online Calculator = 1705 kcal for maintenance (https://tdeecalculator.net)
- Bodyweight in lbs x10 = 1430 kcal for maintenance
- Mifflin St Jeor = 2143 kcal for maintenance
For us to begin a deficit, we simply subtract 15% of the calories from our maintenance TDEE to begin.
However just between these three measures we have a nearly 550kcal range. This could be the difference between a deficit, maintenance and a surplus of calories!
Yet regardless of what approach we choose to select to establish our TDEE, fundamentally only one thing matters. The truest measure of whether we are in a hypocaloric condition, is are we losing weight over time?
Bodyweight tracking over time becomes the gold standard measure of making sure that we are consuming enough calories to create the deficit we require. By selecting a starting point through any of the measures above, then taking the average of the daily calories consumed and the average bodyweight over the first few weeks of our fat loss phase we can create personalised numbers for an individual.
It is important to remember however that creating a deficit is not purely about calorie intake control, whilst this may decrease the Fractional Synthetic Rate of fat tissue (how much fat tissue we put on…), we also have to consider the components of Fractional Breakdown Rate. If we remember back from Effective Body Composition Changes, both our non-exercise activity thermogenesis (NEAT) – how much we move with day-to-day activity, and our exercise activity thermogenesis (EAT) – formal exercise, both contribute to FBR.
We therefore have a balance to establish with TDEE between the caloric deficit we create through food intake, the amount of movement we do day-to-day and the deliberate exercise we perform. As with everything we have discussed so far, there are tradeoffs and downfalls to overemphasising a single component.
The restriction of calories is often the first measure people jump to when trying to establish a calorie deficit. However whilst it’s definitely an effective measure, we need to factor in those barriers we discussed in Upper and Lower Limits of Weekly Fat Loss. Namely that aggressive calorie deficits slow down metabolism and subconsciously reduces our daily activity to preserve energy, thus making it increasingly harder to maintain a calorie surplus over time without further adjustment elsewhere. Likewise we also encounter the psychological and physical challenges of increasing hunger, lower energy levels and likely fluctuations in overall mood.
Increasing our day-to-day activity (NEAT) is an alternative strategy to contribute to a calorie deficit. It is low fatiguing as it can easily be added into the general life activities we all perform. Taking the stairs instead of elevators, walking the dog, walking to a local shop rather than the car etc.
A higher level of NEAT is also strongly correlated within the literature with lower overall bodyweight and lower body fat percentages in individuals that maintain high levels of NEAT day-to-day.
Our third contributor is EAT, the deliberate exercise we perform. This can be resistance training at the gym, classes, swimming, Yoga and the like. Any formal attempt at exercise that doesn’t form part of our day-to-day life. When considering the role of EAT as a contributor to fat loss, we need to look at how each method impacts on calorie burning above normal activity for that time period.
For example, a 60min resistance session at the gym doesn’t burn a huge number of calories in total, especially when we factor in what we would have burned in that time period anyway. Eg. a 60min session with a calorie burn of 300kcal may actually only be 150kcal when we consider we would have burned 150kcal in that 60min period simply by existing…
Cardio exercise (running/cycling/swimming etc…) does burn more calories for the same unit of time as resistance training. However at only 60mins or so per day, it is not a particularly large amount overall compared to alternate sources such as increasing NEAT or restricting food intake. Burning 400kcals running can easily be re-consumed via a post-run snack within 1-2mins.
In our previous post, Typical Timescales for Fat Loss, we spoke of the need to reduce day-to-day variability in caloric intake, NEAT and EAT. It is exactly for the reasons mentioned above that this becomes critical. To remain in a caloric deficit for a sustained period of time, we need consistency.
We can consume a consistent food intake that should create a deficit, however if we range wildly with our NEAT (15,000 steps on Monday, 2000 on Tuesday…), it can be the difference between consistently achieving a goal and rapid fluctuations in rates of loss resulting in periods of maintenance.
Deficit, maintenance and calorie surplus’s are all a balance of food intake, activity and exercise. The ratio of each is dependent upon the individual, their preferences and life circumstances. However, addressing one without factoring in the impact of the remaining is likely to lead to sub-optimal results along the line.
So our takeaway points for todays insight are:
- We can use calculators, formulas or tables to establish an estimation of TDEE. However we must remember these are simply estimates, they are not specific to us as individuals.
- Once our estimated TDEE has been established, bodyweight measurements become the gold-standard for ensuring we are in a consistent calorie deficit.
- Food intake, daily activity (NEAT) and exercise (EAT) are the three factors we are trying to balance day-to-day to maintain our caloric deficit.
- We need to aim to maintain our levels of NEAT consistently throughout a fat loss phase, aiming to build up to approximately 8000-10,000 steps per day.
- Increasing EAT can be a healthy and effective way of increasing caloric deficit levels and can play a key role over time. However an increase in EAT should only be considered when you like to eat more food, you don’t want to reduce food intake anymore, and you have the time and willingness to increase levels of exercise.
- Food intake needs to be carefully balanced based on NEAT and EAT. Lowering food intake should only occur if you can’t increase activity more within reason or don’t want too, you aren’t super hungry or low on energy, and you are already eating objectively plenty of food.
In our next insight we will begin to break down individual Macronutrients and provide some recommendations of daily intake based on individual needs.