When trying to get in shape, anecdotal evidence tells us that at least 80% of your results will be a result of your diet. However it amazes me with all the wealth of information out there now that many people still do not know how to build a diet for themselves.
In this article I will shed some light on how to calculate what you should be eating on a daily basis if you want to be certain of achieving your goals.
Obviously this is general information assuming a good level of health. Consult a doctor if you are unsure before trying a new diet plan.
Your diet will be composed of macronutrients (protein, carbs and fat) and how much you eat of each macronutrient will determine the results you obtain. Each macronutrient has a certain caloric value:
- Protein 4 calories per gram
- Carbs 4 calories per gram
- Fat 9 calories per gram
Actually protein is more like 3.2 calories per gram because there is an energy cost associated with burning protein. But we’ll use 4 as that is the general guideline, so best for simplicity.
Now, the idea to building a diet for yourself is to first of all find out a few basic measurements, calculate a few basic figures, and then use those as the building blocks for your diet. Once you know how to do this process yourself, it becomes very straightforward to get yourself in decent shape fairly quickly. It only takes a bit of learning, and a willingness to measure a bit.
You don’t have to know a huge amount of scientific terms – just a few basic ones.
Basal Metabolic Rate (BMR)
The amount of calories you would need to maintain your bodyweight if you were comatose
Non-Exercise Associated Thermogenesis (NEAT)
The calories from daily activity that is not proper exercise (so not weights, running, sports etc)
Exercise Associated Thermogenesis (EAT)
The calorie requirements associated with your planned exercise regime. Hint: most exercise does not burn as many calories as you think!
Thermic Effect of Feeding (TEF)
The calorie expenditure associated with eating – depends on the macronutrient balance and fiber intake. Eg protein has a high TEF as mentioned above
Total Energy Expenditure (TEE)
The total calorie requirement when all of the above are added together
BMR+NEAT+EAT+TEF = TEE
Lean Body Mass (LBM)
Your bodyweight minus your % of bodyfat
The Katch-McArdle Formula
I have found the Katch-McArdle formula to be the most accurate starting point, especially for those who start out reasonably lean.
However you must have a fairly accurate estimate of your bodyfat % as this is crucial in the calculation.
So, here’s the formula:
BMR = 370 + (21.6 x LBM)
LBM is worked out like this: (total weight in kg x (100 – bodyfat %)) /100
So let’s plug my details into that formula
LBM = 77kg x (100 – 11)) /100
LBM = 68.53kg (we’ll call it 69 kg)
So BMR = 370 + (21.6 x 69)
BMR = 1860 calories
So remember, BMR is the number of calories that I burn completely at rest, if comatose and doing nothing.
To get my TEE we now have to multiply my BMR by an activity factor.
The activity factor should not just take into account your planned exercise, but how active you are generally. If you want accurate results it’s very important to be honest about your activity factor. If you want to lose weight, sometimes better to go too low than too high:
Average activity factors:
1.2: Sedentary (desk job, no exercise)
1.3 – 1.4: Lightly active (light exercise 1-3 times per week)
1.5 – 1.6: Moderately active (moderate daily activity and moderate exercise 3-5x per week)
1.7 – 1.8: Very active (physically demanding life + hard exercise)
1.9 – 2.2: Extremely active (endurance athlete or hard trainer + very demanding job)
So again let’s use my activity factor as an example. Now activity factors can change of course, and this is something to be aware of when making calculations.
At the moment I am fairly inactive (weights 2 or 3 x per week and no cardio) and working from home (God I need to get more exercise!). So my activity factor would be between 1.3 and 1.5. Let’s go for 1.4.
So TEE = BMR x Activity factor (1.4)
TEE = 1860 x 1.4
TEE = 2604 calories
How to use the TEE figure
OK so now we have a fairly accurate figure for our TEE. This is the number of calories we would have to eat, on average, everyday in order to maintain our weight.
Now you have to use the TEE figure to decide what your target calorie intake is going to be based on your personal goals. Goals would be:
Lose bodyweight (bodyfat)
Gain bodyweight (muscle with a little fat)
The simplest way to do it is to use a % of calories to decide your intake. Don’t choose some arbitrary calorie number, such as ‘reduce by 500 calories per day’. 500 calories is a very different proposition for someone who maintains on 4000 calories, than someone who maintains on 1500 calories!
So as an example, if I wanted to lose weight I would start by eating 10-20% less calories per day. Let’s say 15% to start with.
2604 x 0.85 = 2213 calories per day
This would be my starting point for losing weight. The same would go if I wanted to increase bodyweight (to build muscle for example): I would multiply by my TEE by 15% to get my target intake.
How to calculate macronutrients
The macronutrient world is a tricky one to negotiate. There are so many different guidelines out there and the general guidelines given by ‘authorities’ are often woefully inadequate when it comes to performance.
Protein in particular is grossly underestimated in general government guidelines. People who are in training need high protein intakes to fuel recovery and rebuild muscle tissue. Those who are eating to get lean need even higher amounts of protein (relatively) as protein helps keep you full, helps with blood sugar levels and helps maintain muscle mass even when in a calorie deficit.
Therefore I will assume that readers are training (most likely both weights and cardio) and I recommend that bodybuilding/strength training protein guidelines are used – not those of the general medical establishment.
Remember: protein becomes MORE IMPORTANT if you are eating in a calorie deficit, or if you are on a low-carb diet.
- Moderate bodyfat and training load: 2.2-2.8g per kg total bodyweight
- Very low bodyfat/calories or high training load: 2.4-3g per kg total bodyweight
- High bodyfat, high calories or low training load: 1.6-2.2g per kg total bodyweight
Fat is extremely important. There are few things more damaging to your health or sanity that a long-term low fat diet. Fat is involved in almost all of the body’s vital processes and is very important in recovery,muscle regeneration and immune function.
Good fats also help reduce inflammation – great if you are a hard training individual
Average/low bodyfat: 1-2g of fat per kg total bodyweight
High bodyfat: 1.2g fat per kg LEAN bodyweight
There is no such thing as an essential carbohydrate. Carbs have become the staple of of diets due to the agricultural revolution, government subsidies, ignorance of the human body and poverty/rationing.
However carbs are still an important energy substrate and are vital for athletes, those who train very hard or those looking to build mass.
Usually protein and fat requirements should be worked out first with carbs making up the calorie balance. However hard training athletes or endurance athletes may need to calculate carbs first and then work out the protein and fat.
So for most people, especially if trying to lose weight (fat): simply calculate protein and fat needs, then fill up your daily calorie target with carbs. So let’s take my example again:
TEE = 2604
Target = 2604 – 15%… = 2213 calories per day
Protein = 2.5g per kg of bodyweight (2.5 x 77)
Protein = 192g protein per day (at least I would say)
192 x 4 = 768 calories from protein
Fat = 1.4g per kg of bodyweight (1.4 x 77)
Fat = 107g per day
Fat is 9 calories per gram so 107 x 9
= 963 calories from fat
Carbs = Calorie target – (protein + fat)
Carbs = 2213 – (768 + 963)
Carbs = 482 calories from carbs
Carbs = 4 calories per gram
Carbs = 482 / 4 = 120 grams carbs per day
Total calorie target = 2213
Protein = 768 calories (192 grams)
Fat = 963 calories (107 grams)
Carbs = 482 calories (120 grams)
Hopefully these figures and examples give a good idea of how to calculate your own figures for your specific case. Using these you can then build an appropriate diet for yourself.
With a simple Excel spreadsheet you can then adjust and play with your calories and macronutrients over time. You can try some target amounts for a week or two, measure, adjust etc.
In a later article I will go into more detail on macronutrients, what to choose and when to perhaps take your results to another level.