How Much is Enough?

Following on from my previous post in this series, Eating Clean & Getting Fat, which debunked the notion of Unicorns whilst also suggesting two key principles that if followed will provide control over your weight, guaranteed. In this post I will start to fill in some of the blanks. The first question we need to answer is how many calories do I need (on most) days to maintain my weight?  If you are interested in such matters, then read on…

The first Principal states that your diet needs to provide equal calories to those that your body burns. Energy balance. From there, creating an energy deficit will cause you to lose weight, similarly an energy surplus means you will gain weight. This of course begs the question “how many calories is that then?”. The correct acronym for this is TEE or Total Energy Expenditure. There are three ways to establish your TEE:

The simple answer.

A very broad, generic and simplistic answer to TEE would be 2000 calories per day for an adult woman and 2500 for an adult man. And indeed, this is the standard recommendation that you will find on the NHS website. It is not a bad answer and certainly better than not having a clue! For an average woman, consuming 1500 calories per day will probably result in some degree of weight loss. Conversely for the same average adult woman 2500 calories per day will probably result in some degree of weight gain. In very broad terms this gives a starting point and is perhaps “good enough”. Where it lacks sophistication is factoring in levels of activity, age and body type. So whilst it will not be precisely right for virtually anyone, it will be close enough for the average person. But are you average? Or an exquisitely unique individual… I thought so!

The scientifically exact method.

The other end of the spectrum would be to pay for a private clinical assessment with a Dietician in a laboratory setting. This will be expensive and probably not necessary, unless you have been referred by your Doctor as part of resolving a particular issue. The results will be very precise, but unless you have the ability to use the output in an equally precise way, there would seem to be little point.  

The use of a predictive formula.

This is the middle ground, and the technique that I use when starting to plan a weight loss (or maintenance) programme. Several formula exist, but the one that I describe here (and is generally used across many settings) is the Harris Benedict Formula. This takes into account gender, age, height and weight as well as offering a basic approach to modelling the effect of activity. The formula does have limitations which I will also set out for you. 

In calculating your TEE there are three components; however one of these can be safely ignored (dietary induced thermogenesis or DIT) which is the calories you burn in the process of digesting your food. It has a very small impact. 

Let’s look at the two more significant components that we do need to calculate. Firstly your BMR (Basal Metabolic Rate) which (in this context) I am going to use to establish the number of calories a given person would burn at rest. Or put it another way just ticking over sitting on the sofa. The variables we need to know are: gender, age, height and weight. There are a number of calculators free available on the internet to work this out (if you use one make sure it is using the Harris-Benedict Formula). I tend to find it just as quick and easy to do the maths…

Men: 66.5 + (13.75 x weight in kg) + (5.003 x height in cm) - (6.755 x age in years)
Women: 65.1 + (9.563 x weight in kg) + (1.85 x height in cm) - (4.676 x age in years)

Using myself as an example: 

  • 66.5 + (13.75 x 85) + (5.003 x 180) – (6.755 x 52)
  • 66.5 + 1169 + 901 – 351
  • 1786 calories 
  • For simplicity I would round this to 1800 calories per day.

Quite straight forward. But you need to be aware of one error and limitation in the above and that is a lack of consideration for body composition. Muscle tissue (at rest) burns more calories than fat. Which in itself is a good reason for considering developing a leaner body! The leaner your become the more calories you burn whilst sitting on the sofa! It is a beautiful thing and almost then becomes a self-fulfilling prophesy.  The above formula will underestimate BMR for a lean physique. However if you are obese and carrying excess body fat then you will be burning less calories that predicted by this formula. It will over estimate for obese people. But as we are just trying to get a starting point to work with, we need to be aware of the error, but not stress about it! 

The second important element of TEE is the energy (calories) you will burn through normal day to day activity, or indeed exercise. One way to do this, is to use the estimates from your sports watch or FitBit if you have such a device. Alternatively, and a more recognised approach, is to use the following weightings. Simply find the band that best describes your level of activity:

Sedentary (little or no exercise): x 1.2
Lightly active (light exercise/sports 1-3 days/week): x 1.375
Moderately active (moderate exercise / sports 3-5 days/week): x 1.55
Very active (hard exercise / sports 6-7 days a week): x 1.725
Extra active (very hard exercise / sports & physical job or 2 x training): x 1.9

I exercise pretty much every day but most sessions are moderate rather than hard. Therefore I would select “Moderate Active” for myself.

My Total Energy Expenditure would be estimated as being 2,790. This being the number of calories that *should* maintain my bodyweight. As a guide, to lose weight I would cut this by 500 calories per day. I would set myself a daily Calorie Goal of 2,290.  

Please bear in mind that these are estimates! A good starting point for Week 1 and 2, but should be refined based upon how you feel and what the effect on your bodyweight is. Also, all of this modelling assumes a disease-free individual that does not have any conditions that would suggest a specialist meal plan would be appropriate. If you do have a medical condition or disease, it is important that you consult with your Doctor or other healthcare professional.

Now we have an idea of our Total Energy Expenditure, we can divide that by 229 and that gives us the amount of Mars Bars we need to eat each day… (JOKE. And you shouldn’t inject bleach either…). Obviously if we only eat Mars bars each day we would end up a very sorry mess. And that is because we will not have achieved the second principle which is to provide our bodies with all of the Nutrients its needs in order to function correctly. 

If you found this post informative and useful, why not subscribe using the form below and be kept up to date by email when I post new similar content?

In the next post in this series I will cover how to divide up your daily calorie allowance across the three Macro Nutrients. Meal planning from a nutritional perspective. Why fad or restrictive diets don’t work and look deeper into why you can absolutely “Eat Clean and Get Fat”.


Leave a comment