On our personal trainer courses and applied nutrition course, one of the most common questions we receive is, how do you work out the correct amount of calories to advise clients to consume? Well, to begin with, this is not a straight forward answer and it can be a rather complex area, and here is why…
Each individual is different. Each client has a different background, training age and nutritional habits. All of these variables need to be taken into account when you prescribe a nutritional plan and when you’re calculating calories for clients. We have outlined two methods below along with a summary which may help you calculate your client’s calories when you first start working with them:
- Imperial BMR Formula.
During our personal training courses and applied nutrition qualification, we discuss the BMR formula in depth. It is a formula which determines your Basal Metabolic Rate (BMR) by using the following variables – Height, Weight, Gender and Activity Level. Once the BMR is calculated (see formula below) the BMR is then multiplied by an activity level, in most cases this is the Harris Benedict Formula (see table below).
| Gender | BMR Formula |
| Male | BMR = 655 + (9.6 X Weight in KG) + (1.8 X Height in CM’s) – (4.7 X Age in Years) |
| Female | BMR = 66 + (13.7 X Weight in KG) + (5 X Height in CM’s) – (6.8 X Age in Years) |
BMR Formula
| Activity Description | Activity Level |
| Your client is sedentary | 1.2 |
| Your client is lightly active (light exercises 1-3 days a week) | 1.375 |
| Your client is moderately active (moderate exercise 3-5 days a week) | 1.55 |
| Your client is very active (hard exercise 6-7 days a week) | 1.725 |
| Your client is extremely active (very hard exercise / 2x a Day) | 1.9 |
Harris Benedict Formula
Although it seems to use a lot of personal data in its calculations, the BMR formula does neglect to use one of the most important pieces of information, the clients current eating habits. For example, if you consider a 25 years old female client who’s BMR and activity levels result in a calorie total of 2,300 per day, yet she is currently only consuming 1000kcals a day. Without discussing the health concerns associated with long term caloric restrictions like this (immune system dysfunction, endocrine system dysfunction) if you as the trainer then immediately increasing their calories to the BMR recommended 2300kcals per day would result be a number of issues, not least weight and fat gain. During the nutrition delivery on the personal training course, we discuss the other issues associated with this and long term calorie restriction diets in far more detail, but for the purpose of this short blog, let’s keep it simple. Therefore, although the BMR formula and the Harris Benedict equation seem to be scientific and most appropriate method for calculating calorie in take, it does have a major flaw. Having said this, it could be used as a ‘comparison tool’ if you feel a client needs to be made aware of their under eating or lack of total calories
- Food Diary.
I have been a Personal Trainer for 10 years, one thing I notice amongst a number of young trainers is their desire to use the easiest tool, method or protocol when working with clients. In terms of calculating calorie intakes, the BMR formula is relatively easy to do, especially now there are a number of website which calculate it for you. Food diaries in my opinion are the best way to calculate and analyse your client’s eating habits. The only down sides to analysing the food diary thoroughly are time and effort.
By using the food diary to calculate your client’s current calorie in take, you limit the risk of over or under prescribing calories initially. The only major concern with this method is compliance and trust that your client will be honest. A top tip here, take the first couple of days of the food diary with a pinch of salt. Over the years I have come to the conclusion that when individuals are being assessed they will automatically change their behaviours to what they believe the assessor expects. For example, days 1 and 2 of a food diary may see the morning ‘brew’ be accompanied by a piece of fruit, but as the week goes on that piece of fruit turns into a biscuit, then two biscuits and then three as their behaviour returns to their normal habits. It’s just human nature, nobody likes to be judged!
Another bonus to using the food diary as a method of analysing calorie in take is all the other information you can get from it:
- Food quality (processed, organic)
- Meal timings
- Meal frequency
- Water consumption
- Alcohol in take
- Portion size
- Trigger foods!
Trigger foods is something else we discuss in great detail on the personal training courses. As a trainer we need to be aware of trigger foods, so we can help our clients not only stay away from them but hopefully increase their willpower and ability to control those cravings.
For example, if a client’s food diary demonstrated that every time they had ice cream they finished the whole tub and then went on to eat half a pack of chocolate hobnobs and some crisps, but this only occurs after ice cream, then it is clear to me that ice cream is a trigger food which results in poor self control and the consumption of high calorific foods. Therefore, my nutrition advice for that client would include, ‘stay away from ice cream’, for the short term anyway. As self control improves and the client becomes more educated we can reintroduce some ice cream in to their diet.
In conclusion, during our personal training courses we strongly recommend analysing the client’s food diary in great detail as form of calculating their calorie requirements and in take. The benefits of this are specificity to the client, their current eating habits and also all the the extra information you can get from your client e.g. trigger foods.