1/ BMR (Basal Metabolic Rate): This is the amount of calories you need to consume to maintain your body if you were comatose (base level).
2/ NEAT (Non-Exercise Associated Thermogenesis): The calorie of daily activity that is NOT exercise (eg: washing, walking, talking, shopping, working). ie: INCIDENTAL EXERCISE! It is something that everyone has a good amount of control over & it is the MOST important factor in your energy expenditure. It is what helps keep ‘constitutionally lean’ people LEAN (they fidget)!
3/ EAT (Exercise Associated Thermogenesis): The calorie requirements associated with planned exercise. Unless someone is doing a whole heap of exercise (eg: two or more hrs training a day) it usually doesn’t add a stack of calories to your requirements (30 minutes of ‘elliptical training isn’t going to do it’)
4/ TEF (Thermic effect of feeding): The calorie expenditure associated with eating. REGARDLESS of what myths you have been told – this is NOT dependent on MEAL FREQUENCY. It is a % of TOTAL CALORIES CONSUMED (and 15% of 3 x 600 cal meals is the same as 15% of 6 x 300 cal meals). It varies according to MACRONUTRIENT content and FIBER content. For most mixed diets, it is something around 15%. Protein is higher (up to 25%), carbs are variable (between 5-25%), and fats are low (usually less than 5%). So -> More protein and more carbs and more fiber = HIGHER TEF. More FAT = LOWER TEF.
5/ TEE (Total Energy Expenditure): The total calories you require – and the sum of the above (BMR + NEAT + EAT + TEF).
How much do you need?
- There is therefore a multitude of things that impact a person’s MAINTENANCE calorie requirements
- Age & sex (males generally need > females for any given age)
- Total weight & lean mass (more lean mass = more needed)
- Physiological status (eg: sick or injured, pregnant, growth and ‘enhancement’)
- Hormones (eg: thyroid hormone levels, growth hormone levels)
- Exercise level (more activity = more needed)
- Daily activity level (more activity = more needed)
- Diet (that is – macronutrient intake)
In order to calculate your requirements the most accurate measure is via Calorimetry [the measure of 'chemical reactions' in your body & the heat produced by these reactions], either directly (via placing a calorimeter where the heat you produce is measured) or indirectly (eg: HOOD studies where they monitor how much oxygen you use/ carbon dioxide and nitrogen you excrete over a given time). But although accurate they are completely impractical for most people & we mostly rely on pre-set formula to calculate our needs.
NOTE: IF YOU ARE LESS THAN 18 YRS OF AGE – THESE FORMULA WILL NOT BE ACCURATE!There is an energy cost associated with growth / inefficient movement / high surface area:mass ratio. Look HERE for alternatives.
As a teenager I would also STRONGLY suggest you don’t obsess on calories and macros! Eat well, exercise regularly, and have fun while you can!
The simplest method is to base your intake on a standard ‘calories per unit of weight (usually kilograms)’. Typically:
- 26 to 30 kcals/kg/day for normal, healthy individuals with sedentary lifestyles doing little physical activity [12.0-14 kcal/pound]
- 31 to 37 kcal/kg/day for those involved in light to moderate activity 3-5 x a week with moderately active lifestyles [14-16 kcal/ pound]
- 38 to 40 kcals/kg/day for those involved in vigorous activity and highly active jobs [16-18 kcal/ pound].
- For those involved in HEAVY training (eg: athletes) – the demand is greater:
- 41 to 50 kcals/kg/day for those involved in moderate to heavy training (for example: 15-20 hrs/ week training) [18.5-22 kcal/ pound]
- 50 or above kcals/kg/day for those involved in heavy to extreme training [> 22 kcal/ pound]
There are then a number of other formula which calculate BMR. This means it calculates what you need should you be in a coma.
1/ Harris-Benedict formula: Very inaccurate. It was derived from studies on LEAN, YOUNG, ACTIVE males MANY YEARS AGO (1919). Notorious for OVERESTIMATING requirements, especially in the overweight. IF YOU CAN AVOID IT, DON’T USE IT!
MEN: BMR = 66 + [13.7 x weight (kg)] + [5 x height (cm)] – [6.76 x age (years)]
WOMEN: BMR = 655 + [9.6 x weight (kg)] + [1.8 x height (cm)] – [4.7 x age (years)]
2/Mifflin-St Jeor: Developed in the 1990s and more realistic in todays settings. It still doesn’t take into consideration the differences as a consequence of high BF%. Thus, once again, it OVERESTIMATES NEEDS, ESPECIALLY IN THE OVERWEIGHT.
MEN: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] – [4.92 x age (years)] + 5
WOMEN: BMR = [9.99 x weight (kg)] + [6.25 x height (cm)] – [4.92 x age (years)] -161
3/Katch-McArdle:Considered the most accurate formula for those who are relatively lean. Use ONLY if you have a good estimate of your bodyfat %.
BMR = 370 + (21.6 x LBM) Where LBM = [total weight (kg) x (100 - bodyfat %)]/100
As these are only BMR calculations To convert BMR to a TOTAL requirement you need to multiply the result of your BMR by an ‘activity variable’ to give TEE.
The Activity Factor is the TOTAL cost of living and is BASED ON MORE THAN JUST YOUR TRAINING. It includes work, life activities, training/sport & the TEF of ~15% (an average mixed diet).
Average activity variables are:
- 1.2 = Sedentary (Little or no exercise + desk job)
- 1.3-1.4 = Lightly Active (Little daily activity & light exercise 1-3 days a week)
- 1.5-1.6 = Moderately Active (Moderately active daily life & Moderate exercise 3-5 days a week)
- 1.7-1.8 = Very Active (Physically demanding lifestyle & Hard exercise or sports 6-7 days a week)
- 1.9-2.2 = Extremely Active (Hard daily exercise or sports and physical job)
How Accurate are they? They give rough ball-park figures and are still ‘guesstimations’. So the aim is to use these as ‘rough figures’, monitor your weight/ measurements for 2-4 weeks, & IF your weight is stable/ measurements are stable, you have likely found maintenance.
Using the Above to Recalculate Based on Goals
You then need to DECREASE or INCREASE intake based on your goals (eg: lose or gain mass). It is not recommended to use a ‘generic calorie amounts’ (eg: 500 cals/ day). Instead this should be calculated on a % of your maintenance. Why? The effect of different calorie amounts is going to be markedly different based on someones size/ total calorie intake. For example – subtracting 500 cals/ day from a 1500 total intake is 1/3rd of the total cals, where 500 cals/ day from 3000 total intake is only 1/6th of the total. The results will therefore be markedly different on an individuals energy level & weight loss. Generally:
- To ADD weight: ADD 10-20% calories to the total above
- To LOSE weight: SUBTRACT 10-20% calories from the total above
Then monitor your results and adjust as required.
Once you work out calorie needs, you then work out how much of each macronutrient you should aim for. This is one of the areas that is MOST often confused but This should NOT be based on a RATIO of macro intakes. (eg: ’30:40:30 or 40:40:20′) Your body doesn’t CARE what % intake you have. It works based on SUFFICIENT QUANTITY per MASS.
So to try to make it as simple as possible:
1. Protein: Believe it or not – Protein intake is a bit of a controversial issue. In this, the general recommendations given in the ‘bodybuilding’ area are nearly double the ‘standard’ recommendations given in the Sports Nutrition Arena.
The GENERAL sports nutrition guideline based on clinical trials suggest that in the face of ADEQUATE calories and CARBS the following protein intakes are sufficient:
- STRENGTH training -> 1.2 to 1.6g per KG bodyweight (about .6 / pound)
- ENDURANCE training -> 1.4 to 1.8g per KG bodyweight (about .8 / pound)
- ADOLESCENT in training -> 1.8 to 2.2g per KG bodyweight (about 1g / pound)
BUT researchers acknowledge that protein becomes MORE important in the context of LOWER calorie intakes, or LOWER carb intakes.
Recent evidence also suggests that protein intakes of 3g/kg help with physiological and psychological stressors associated with high volume or intense training
It is important to note that ADEQUATE v’s OPTIMAL is not discussed. And one also needs to consider thermogenics/ satiety/ and personal preference.
General ‘bodybuilding’ guidelines for protein would be as follows:
- Moderate bodyfat = 1-1.33g per pound TOTAL weight [or ~ 1.25g/pound lean mass if bodyfat known]
- Very Low bodyfat or Very Low Calorie = 1.25 – 1.75g per TOTAL weight [or ~ 1.35 - 2g/pound of lean mass]
- Very HIGH bodyfat, Inactive, = 0.8 to 1g per TOTAL weight [or ~ 1 x LEAN mass]
Anecdotally, most find these HIGHER protein intake better for satiety, partitioning, and blood sugar control. So UNLESS you are specifically guided to use the GENERAL sports nutrition guidelines, I would suggest the BODYBUILDING values.
2. Fats: Generally speaking, although the body can get away with short periods of very low fat, in the long run your body NEEDS fat to maintain general health, satiety, and sanity. Additionally – any form of high intensity training will benefit from a ‘fat buffer’ in your diet – which acts to control free radical damage and inflammation. General guides:
Average or lean bodyfat: 1 – 2g fat/ kg body weight [between 0.40 - 1g total weight/ pounds]
High bodyfat: 1-2g fat/ LEAN weight [between 0.4 - 1g LEAN weight/ pounds]
IF low calorie dieting – you can decrease further, but as a minimum, I would not suggest LESS than about 0.30g/ pound.
Note 1: Total fat intake is NOT the same as ‘essential fats’ (essential fats are specific TYPES of fats that are INCLUDED in your total fat intake)…
3. Carbs: For carbs there are no specific ‘requirements’ for your body so – but carbs are important for athletes, HIGHLY ACTIVE individuals, or those trying to GAIN MASS. [carbs help with workout intensity, health, & satiety (+ sanity)].
If you are an athlete involved in a good volume of training I would suggest you CALCULATE a requirement for carbs as a PRIORITY – then go back and calculate protein / fat:
- Moderately active: 4.5 – 6.5 g/ kg (about 2 – 3g/ pound)
- High active: 6.5 – 8.5 g/ kg (about 3 – 4g/ pound)
- INTENSE activity: + 8.5g / kg (more than 4g/ pound)
For ‘other folk’ – to calculate your carbohydrate intake you simply use it to fill in the calories left over from fats/ protein:
carb calories = Total calorie needs – ([protein grams as above x 4] + [fat grams as above x 9])
carbs in grams = above total/ 4