Wednesday, June 6, 2012

Number Crunching: Calculating Calories and Macronutrients

Number Crunching: Calculating Calories and Macronutrients

This article is written by Charli.

How many calories should I be eating? How much protein, how much fat, how many carbs? What amount to gain muscle? How much to lose fat?

These are incredibly common questions, but rarely can we find a good answer to them. And unfortunately, this is why so many of us stall in our progress. Inadvertently overeating, or undereating, is a widespread dietary dilemma, and one that could so easily be avoided, with the right information.

Here, I will provide you with a user-friendly guide to calculating your nutritional needs, and designing your diet.

Before we get started, here’s a glossary of terms that you’ll need to familiarise yourself with:

BMR (Basal metabolic rate)

This is the amount of calories that you’d need to consume to maintain your body if you were completely inactive (i.e. comatose, or bed-ridden). Many dieters confuse their BMR with their TEE (which we’ll get round too)- a misunderstanding that leads to eating far fewer calories than the body actually requires. This is an all-too-common cause of diet failure, so knowing your dieting lingo is very important!

EAT (Exercise Associated Thermogenesis)

EAT is the calorie requirements associated with planned exercise (i.e. your workout routine). This is something that many people grossly overestimate. Unless someone is doing a monumental amount of exercise each day (e.g. an endurance athlete), EAT won’t add a tremendous number of calories to your requirements.

NEAT (Non-Exercise Associated Thermogenesis)

NEAT is the calorie requirements associated with incidental exercise (e.g. housework, shopping, general moving around). This tends to represent the largest variable in someone’s daily calorie requirements, as it’s affected by the nature of their job, their home life, their social life etc. It is, however, something that can easily be increased, in order to burn more calories.

TEF (Thermogenic Effect of Feeding)

TEF is the calorie expenditure associated with eating. It varies according to macronutrient and fibre content (and NOT according to meal frequency, as many would have us believe). For an average, balanced diet, TEF is around 15%. Protein is the most thermogenic macronutrient (with TEF up to 25%), carbs are variable (between 5-25%), and fats are the least thermogenic (usually less than 5%). More protein + more carbs + more fiber = higher TEF. More FAT = lower TEF. But let me press home that this does NOT mean a low fat diet is better!

TEE (Total Energy Expenditure)

TEE is the total calories your body requires (so that’s BMR + NEAT + EAT + TEF). This is more commonly referred to as ‘Maintenance Calories’, i.e. the number of calories required to maintain your body, based on your current lifestyle.

So here are all the factors and variables that determine your TEE:

Age (metabolism generally decreases as we get older)
Gender (males generally need more than calories than females)
Total weight and lean mass (more lean mass means a higher TEE)
Daily Activity Level (a higher activity level means a higher TEE)
Exercise (more exercise means a higher TEE)
Diet (what it’s comprised of)
Physiological Status (e.g. sick, pregnant, growing)
Hormone Levels (e.g. thyroid hormone levels, growth hormone levels)

Estimating TEE

Unless you’re able to snag yourself a TEE assessment via Calorimetry (a process in which a calorimeter is used to measure chemical reactions in your body and the heat produced by these reactions) then you’ll have to opt for the less accurate, but rather more convenient methods of TEE calculation.

There are a number of ways in which estimate TEE- some better than others- all of which we will run through now.

The simplest (and thus, often least accurate) method is to estimate TEE using a standard 'calories per unit of weight'. These standard figures are as follows:

For sedentary individuals partaking in little exercise:
25-30 calories/kg/day (11.5-13.5 calories/lb)

For moderately active individuals partaking in light-moderate exercise:
30-35 calories/kg/day (13.5-16 calories/lb)

For highly active individuals partaking in vigorous exercise:
35-40 calories/kg/day (16-18 calories/lb)

There are also several more complex formulae, which calculate BMR based on variables including sex, height, weight, age, and lean mass. This BMR is then multiplied by an 'activity factor' to give TEE.

These formulae vary greatly in terms of accuracy, due to the circumstances in which they were tested. Here are two of the more accurate BMR calculations:

The Mifflin-St Jeor Formula

For Women: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] - [4.92 x age (years)] -161


This is a reasonable formula for the average individual, as it was devised in a way that makes it realistic in today’s environment. However, it does not factor in the difference in metabolic rate as a consequence of BF% levels. This means that it overestimates needs in highly obese individuals, and can underestimate requirements for very lean individuals. So be warned!

The Katch-McArdle Formula:

Note: LBM stands for ‘Lean Body Mass’ (i.e. everything in your body that isn’t fat- muscle, bone, water etc).

BMR = 370 + (21.6 x LBM)

Where LBM = [total weight (kg) x (100 - bodyfat %)]/100

This is the most accurate formula for relatively lean individuals who have a good understanding of their bodyfat %.

Now, if you’ve used one of these two formulae, don’t forget that all you have at the moment is your BMR! It’s now necessary to multiply that number by an ‘activity factor’ to convert it to an estimation of your TEE.

The activity factors are as follows:

1.2 = Sedentary (little or no exercise and desk job)
1.3-1.4 = Lightly Active (light exercise or sports 1-3 days a week)
1.5-1.6 = Moderately Active (moderate exercise or sports 3-5 days a week)
1.7-1.8 = Very Active (hard exercise or sports 6-7 days a week)
1.9-2.0 = Extremely Active (hard daily exercise or sports and physical job)

Note: These activity factors already include a TEF of around 15% (an average mixed diet).

CAUTION: DO NOT RELY ON THESE CALCULATIONS! They give a rough ball-park figure to use as a starting point, but they are rarely accurate. Most people overestimate their activity factor, and underestimate their bodyfat, which means that they OVERESTIMATE their calorie requirements. So start with these rough figures, and then monitor your body measurements for 3-4 weeks (it’s important you allow sufficient time to get an accurate idea of what’s going on). You can monitor your weight as well, but due the vast number of variables responsible for weight fluctuation, measurements are far more accurate gauge. If your measurements remain stable, then you have likely found your maintenance calorie requirements (your TEE). Otherwise, adjust your intake accordingly and repeat the process.

It can sometimes take a little while to discover the right maintenance intake, and bear in mind, TEE will vary as your body and activity levels change. However, it’s essential to take the time you need to find the right number for you, because it’s going to make setting up a diet for your ultimate body goal so much easier!

Once you’ve deduced your TEE, you will then need to increase or decrease intake, based on your goals of increasing lean mass or decreasing bodyfat. Base this calorie increase or reduction on a percentage of your TEE, rather than on a generic number (the suggestion of ‘+/- 500 calories’ gets thrown around a lot). There is no one-size-fits-all surplus or deficit, due to the huge variations in each individual’s calorie requirements.s

Some good, guideline percentages are as follows:

To gain weight: Add 10-20% calories to your maintenance requirements (TEE x 1.1-1.2)

To lose weight: Subtract 10-20% calories from your maintenance requirements (TEE x 0.8-0.9)

Then monitor your results and adjust as required.

For those looking to gain muscle, a 10-20% surplus will generally minimise fat gain, and for those looking to lose fat, a 10-20% deficit will generally minimise muscle loss and energy/performance issues. This, of course, needs to be in combination with a good macronutrient breakdown and an appropriate training programme.

Macronutrient Needs

Now we’ve got the calorie equations out of the way, it’s time to look at how we should be making up those calories, i.e. the minimum requirements for each macronutrient. This should be based on your bodyweight and lean mass, NOT on a percentage of your calorie intake. Despite what some may have you believe, there aren’t any one-size-fits all, magic ratios.

1. Protein

When I talk about minimum protein requirements, I’m referring to the minimum that is optimal for muscle gain, or muscle preservation. This applies to anyone with goals of improving body composition, who is training with that goal in mind. It is NOT the minimum in terms of essential requirements. But if you don’t want an average body, you don’t want an average diet.

I would recommend a minimum intake of 1-1.5g/lb lean mass. If you don’t know your lean mass, calculate a ballpark figure of 1-1.5g/lb total bodyweight. If you use the latter calculation, bear in mind that lean individuals need to aim closer to 1.5g/lb, whereas those with a higher bodyfat % needn’t be looking at more than 1g/lb.

2. Fat

When talking about fat intake, I am referring to total fat. This should include essential fats (from poly- and monounsaturated fat sources), but is not limited to them.

For optimal health, hormone function and overall results, those following a moderate diet should be consuming at least between 0.35-0.5g/lb lean mass. Again, if you’re unsure of your lean mass, use your total bodyweight, with lean individuals using the higher number, and those with a higher bodyfat % working with the lower number.

Generally, a higher fat intake is required by those on low-carb diets, with up to 1g/lb lean mass being common with ketogenic type diets.

3. Carbs

There are no specific requirements for carbs. If you’re highly active, involved in endurance sports, or trying to gain mass, then a higher carb intake will be optimal, to fuel your workouts and your body. If you’re activity level is lower, or if you’re dieting, carbs will be lower. At this point, it’s a case of finding the balance that works best for you, in terms of energy and satiety. Once you’ve met the protein and fat minimums, you can simply fill the remainder of your calories with carbs. Alternatively, you may want to try a combination of carbs + more of the other macronutrients (in this instance, protein would usually stay the same, and fat would be increased).

Protein and carbs both contain 4 kcal/g, and fat contains 9 kcal/g, so to work out how many grams of carbs you require, you’ll need to do the following equation:

Total calories = ([protein grams x 4] + [fat grams as x 9]) divided by 4

You will likely benefit from using a calorie tracking website, or calorie tracking software. This will save lots of time and confusion, especially in the initial stages of designing your diet. Some free tracking websites I would particularly recommend are NutritionData, Sparkpeople, DailyBurn and Nutridiary. Each provides a large database of both generic and brand name foods, with the additional option of creating your own custom foods and meals. Calorieking is another good site- it doesn’t provide a free tracking facility, but it offers an incredibly extensive nutrition database.

Don’t feel that you have to track every day- it simply needs to be often enough so as to have a good awareness of your dietary intake, and so as to familiarise yourself with nutritional content and serving sizes of various foods. Of course, you may prefer to track daily, and if that’s the case, by all means, go for it! Again, it’s all a case of tailoring everything to your own needs.

So there you have it- all the information you require to get crunching those numbers and applying them to your diet! Once you’ve established the basis of your requirements, it’s simply a case of tweaking the diet as necessary, to make it as effective for you as possible. Best of luck, and happy eating!

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