How To Calculate Your Energy Requirements

Energy balance is an important component of the alteration of body composition. Energy balance is difference between energy intake minus energy expenditure. 

Energy balance = energy in – energy out

A positive energy balance is associated with weight gain and a negative balance with weight loss. Similarly, muscle gain is associated with a positive energy balance and fat loss with a negative balance. This is not a steadfast rule - you can gain muscle in an energy deficit and lose fat during a surplus - but we can worry about that later.

 

ASSESSING ENERGY INTAKE

Energy intake can be calculated quite simply and is typically derived from macronutrient intake. By weighing foods and using food labels/tracking applications such as Easy Diet Diary (iPhone only) or My Fitness Pal (any device) you are able to estimate and begin to understand your daily energy intake. 

It is important to understand the difference between accuracy and reliability, with regards to assessing energy intake. Accuracy is the precision of the assessment - is the assessment correct? It is difficult for applications and estimates to be accurate, because each food can vary based on numerous factors such as cooking method, duration and storage, among many others. 

Reliability is the consistency of the assessment - does it constantly deliver the same result? Apps deliver the same result, which makes them reliable. While the accuracy can be questioned, this measurement error remains consistent across all assessments. Therefore, our current assessment tools (apps, equations, tracking) are reliable with potential inaccuracies

An easy way to consider the difference between accurate and reliable assessments is to think of a dartboard. Accuracy would be defined as hitting the target, which in this case is the bullseye. Reliability could be missing the bullseye, but having a consistent grouping in the top right. Ideally we want an assessment that is both accurate and reliable, but this technology does not currently exist in this field. 

Reliability is more important that accuracy when it comes to assessing energy intake and expenditure. Weighing foods, estimating energy expenditure is an imperfect science. One application might list chicken breast as containing 250kcal where another might list 300kcal, but this OK. Either measurement provides a quantification of food intake that can be altered in the future. 

What really matters is that we can manipulate energy balance to achieve a desired outcomes. If we assess your food intake for a week and you have lost weight, this indicates an energy deficit was in place. Whether we estimate energy intake to be 2000kcal or 2500kcal, what matters is that the ACTUAL food intake is adjusted, relative to the clients needs. 

 

ASSESSING ENERGY EXPENDITURE

Establishing energy expenditure is slightly harder to do, but here are the methods we use. We have not mentioned the components of energy expenditure, as the focus is on assessment methods. Most people don't need to know their estimated thermic effect of food (TEF) they just need to know how much to eat and exercise to achieve their goals.

 

OK: Estimation

There are numerous equations and application that can predict your energy expenditure. Age, gender, height, weight, activity level and nutrient intake are some of the multitude of factors that can determine your energy output. Some equations use more factors than others, although this does not necessarily increase accuracy.

These equations are a useful start point, but they do come with limitations. For example, they cannot take into account previous energy intake and potential metabolic adaptations. This can be problematic for people who have been dieting long term – which are often the people who want to use these equations.

The following equation is one of the most simple and can be used as a starting point. I would avoid reading too much into height, age, estimating body composition, etc. While they look great on paper and you feel like Einstein feeding them into the calculations, the reality is they just add further data to an imprecise equations.

Male: 24 x body weight (in kg)       Female: 22 x bodyweight (in kg)

Results are the multiplied by physical activity level. For someone going to the gym for about an hour, a multiplier of 1.3-1.9 seems to suit, but this should be tested and assessed through practical application.

The next step would to be introduce tracking and monitor results (see next point). My biggest learning from the past 21 months is the need to track actual intake - not rely on equations - to provide the correct starting point for success. I cannot confidently say you need to eat x amount of calories for weight loss for weight gain, based on an equation that measure 2-6 data points. By tracking the practical applications, we can gauge the appropriateness for the individual.

 

Good: Tracking

Another method is to skip the estimations and just track energy intake for the first few weeks. This is now my preferred method of accurately understanding energy intake while gaining an insight into foods and times a client likes to eat.

When I first started out, I felt the need to prescribe recommendations from day one. Now I can see the benefits from implementing and refining a tracking component.

Weight, energy levels, exercise performance and sleep can all be assessed on this food intake, to determine its suitability. If the client feels hungry and loses weight, this intake is likely below their maintenance and they are in an energy deficit.

The added benefit is the client contributes to the initial nutrition recommendations that you provide them. The emphasis is on refining their intake, instead of prescribing mine. Over time, they will gravitate to the desired end product, which is often a very different nutrition intake to what they consumed previously. However, avoid the huge change early on is beneficial to long term adherence.

The best thing to hear from a client is “that wasn’t too hard” or “we didn’t change much” while achieving results on a program. Small and progressive alterations will deliver the best results in the medium to longer term, and ideally should never feel too hard to implement.

 

Best: Combination of Estimation and Tracking

The method we now use on the Body Recomposition Program is a combination of estimation and then reviewing its implementation by tracking. This allows to assess the efficacy of a given energy intake and provide a base for future programming decisions.

This provides the quantification from estimates combined with the practical assessment of tracking. From this point, we have a holistic understanding of the client’s energy expenditure.

When it comes to making judgements of energy intake and making recommendations, there is significantly more data from a combination of accurate and reliable sources. This allows the recommendations to work immediately.

 

Summary

Understanding your daily energy requirements is the basis of any nutrition program aiming to support body recomposition and/or performance. Equations provide an estimated starting point, but a combination of estimation and tracking provides superior data for the professional. Although it takes longer to create, this will lead to greater results in the longer term.

Beware of the limitations of each method and try to incorporate reliability into your assessment of energy expenditure.