Chapter 9: Prescription – Macros

Chapter 9: Prescription – Macros


There are multiple ways to determine an appropriate caloric intake for a client, but for the purposes of this text we will provide you with 3:

  1. Using TDEE
  2. Alan Aragon Formula
  3. Multiplier System

1. Using TDEE

TDEE – Recall from earlier that Total Daily Energy Expenditure is the sum of your BMR (basal metabolic rate), EA (exercise activity), NEAT (non exercise activity thermogenesis) and TEF (thermic effect of feeding).

Unfortunately, it is very difficult to know the exact number of calories burned via our NEAT, EA, and TEF, so to determine TDEE we simply take our BMR (measured from the Harris-Benedict equation) and use an intensity multiplier.

The intensity multiplier scale is a measure of the type, intensity, duration and frequency of physical activity as follows:

Little to no exercise, desk job = BMR x 1.2

Light exercise, trains 1-3 days weekly = BMR x 1.375

Moderately active, trains 3-5 days weekly = BMR x 1.55

Very active, trains 6-7 days weekly = BMR x 1.725

Extreme activity, double-day training and/or intense physical job = BMR x 1.9

Once you know your TDEE you can now prescribe the correct caloric intake relative to individual goals.

Weight gain would yield a prescription of TDEE + 300-500 calories.

Weight loss would yield a prescription of TDEE – 300-500 calories.

Weight maintenance would yield a prescription of TDEE.

2. The Aragon Formula

While this formula is not widely recognized in traditional textbooks, we have found that it’s application is very simple to use and provides outstanding results.

Alan Aragon is a pioneer in helping to understand the scientific research that is always being conducted. Very few of us have the time to regularly sift through scientific journals and interpret the data. Aragon does this monthly in his research review – it is a product we highly recommend following.

His formula is as follows:

Calories = Target body-weight x (number of training sessions weekly + intensity training factor)

Intensity Training factors for this formula are as follows:

Women: 8/9/10

Men: 9/10/11

The key to this formula is to understand factors that can affect the training intensity factor. Obviously things like training modality and duration will come into play, but some not so obvious things like training age and skill proficiency must also be considered.

3. The Multiplier System

In general, the multiplier system is the least accurate. We are only listing it as we feel it is necessary to provide you with tools that are commonly used. You will likely be asked about it at some point so a fundamental understanding of it is important.

The original multiplier system is as follows:

Fat loss = BW(bodyweight) x 10-12

Maintenance = BW x 13-15

Weight Gain = BW x 16+

However, those formulas were developed several years ago. Since then the overall intensity of training modalities has risen tremendously and that needs to be accounted for. The multiplier system that we feel is more accurate is:

Fat loss = BW x 12-14

Maintenance = BW x 15-16

Weight Gain = BW x 17+

Note: It is always best to err on the side furthest from a client’s goals when creating the initial prescription (i.e the high side for fat loss and the low side for weight gain). This will give you a definitive direction to take the calories when making changes.

When to NOT use a formula

The formulas listed above are all based on sound, scientific research and assuming all things are normal, they work.

Unfortunately this is the real world and not all things are normal.

Let’s assume that the formulas above gave you a caloric prescription of 2000 calories for fat loss.

However your current consumption is only 1000 calories.

Doubling your calories will likely NOT yield the fat loss that the formulas were built for.

This is when you must employ logic and slowly begin a reverse diet (explained in Chapter 15.)

Now let’s use the same example but on the opposite side of the spectrum. What if the formulas gave you a fat loss prescription of 2000 calories but you are currently consuming 3500 calories daily. Do you really think that a near 50% reduction in calories is necessary? Probably not! Instead, try reducing current calorie intake by 20% which will yield far less hunger and more energy!


At this point you should understand that a proper macro prescription comes from having a proper caloric prescription and you should understand how to achieve the caloric prescription for your client.


To begin your macro prescription always start with protein.

We discussed earlier in this text that the RDA is extremely low when it comes to protein consumption. Alternatively, some modern recommendations call for 0.8- 1.2g protein/lb lean body mass – this recommendation works very well.

A final alternative would simply to be use 1g/lb of current bodyweight, or 1g/lb of target bodyweight for the obese clientele.

A few things to consider when assigning a protein intake for a client:

  • In a calorie surplus, protein intake can be lower due to the protein sparing effects of increased carb and fat intake
  • In a calorie deficit, protein intake must be maximized due to the absence of protein sparing nutrients

Also recall from earlier that protein has the highest thermic effect of all three macros (another reason to maximize protein intake during a fat loss phase).

A final consideration would be to first look at your client’s current protein intake. Similar to overall calories, you do not want to create an environment where this target is not realistic or will cause negative effects. Example – if your protein prescription comes out to 200g, but your client’s current protein intake is 100g, you may have to slowly transition your client to the higher intake. DO NOT alter your calorie prescription, simply redistribute the extra calories to carbs or fats (depending on individual needs).

Refer to chapter 4 if a client has questions on protein sources.

Once you have your protein intake established, multiply this number by 4 and you will have the total number of calories assigned to protein intake.


The next step is to determine fat intake.

There are two ways to go about this:

The first way is a multiplier system of using 0.3-0.5g fat/lb LEAN body mass.

While this formula will work for a lot of people, it does not seem to have a great application in a more athletic population. It also does not allow for assessment of a client’s insulin sensitivity to be used.

Instead, we prefer assigning fat as a percentage of total of calorie intake.

This will yield a large range – from 20-70% of total calories. The higher end of this range (60-70%) is typically reserved for a ketogenic approach but the rest of the range will depend on a few variables:

  • Current body composition
  • Training age
  • Current dietary intake
  • Energy system demands of training
  • Hormonal status

Charles Poliquin coined the phrase “earn your carbs” and while we are not in total agreement with this statement, it does have some validity – specifically in terms of fat prescription relative to body composition. When viewing this variable in isolation we can conclude that the more body fat an individual currently has, the less carbohydrates they “need.” Obviously the factors below will have an impact but as a general rule this seems to work.

Training age is another important variable to consider. Recall that when an individual undertakes a new activity such as resistance training there is a neurological adaptation phase. This is to say that a person is learning “how to” do new things rather than creating performance adaptations which diminishes the “need” for carbohydrates in the diet.

Similar to both calories and protein, current intake MUST be assessed when viewing fat calories. If a client has poor body composition and a low training age but is currently only consuming 20% of total calories from fat, do NOT immediately jump them to 45-50% of calories. This will require a slow transition as to ensure compliance and/or GI health.

The energy system demands of the current training protocol must also be considered. Note the use of the word CURRENT, as this can vary at different times of a periodized program. Just because an athlete is a “crossfit athlete” does not automatically mean they need more carbs than fats. Perhaps they are in their “off season” and prioritizing absolute strength accumulation – this would not yield the same prescription as during their competition or “in season” phase.

Hormonal status is another important factor to consider. While this course is not going to go into great detail about hormonal issues, it is worth noting that dietary fat consumption can be important in the hormone rebuilding process. Recall that cholesterol is a precursor to testosterone production and therefore can aid in maintaining a positive hormonal profile.

Once you have taken everything above into account we tend to see fat prescriptions as follows:

20-30% – leaner individuals looking to lose the final amounts of fat OR performance athletes that are in season.

30-50% – athletes with more body fat to lose OR performance athlete that are off season OR performance athletes whose sports are not glycolytic in nature

60-70% – ketogenic diets OR clients with pre-diabetic considerations OR clients with purely seeking longevity with little to no exercise

Once you define this percentage of calories, figure out what this represents as a calorie number then divide by 9 and you will have found your fat macronutrient prescription.

If you need examples of quality fat sources refer to Chapter 4.


The final macro left for prescription is carbohydrates. At this point you know the number of calories you want your client to consume and you have also allocated calories for proteins and fats. Add the calories allocated for proteins and fats together and subtract that number from the total caloric prescription. This number is the number of calories your client will consume from carbohydrates.

Now divide this number by 4 and you will have the number of grams of carbohydrates you will be prescribing to your client.

Once again, similar to calories, proteins, and fats – this number should not be too great of a deviation from their current intake. (You will not take a client on a keto diet to an intake of 300g carbs). However, if you have taken proper care when prescribing proteins and fats this should not be the case.

Several of the variables that influence fat prescription will also influence carbohydrate prescription but because you accounted for them when calculating fat intake they have also been accounted for in carbohydrate intake. However, they are worth reviewing to ensure you have properly gone through the process.

As a review:

  • Current body composition can influence the prescription. The leaner an individual, the more carbohydrate they can consume (yielding a lower percentage of fats).
  • The greater the training age, the more carbohydrate that is NEEDED for higher intensity activities.
  • Current dietary intake will require a review of all prescriptions as to not create an excessive deviation away from current intake
  • Training demands, specifically glycolytic work, will require more carbohydrate for fuel and subsequent recovery
  • An individual, regardless of all other factors, that has an impaired hormonal profile will typically require more dietary fat intake which will yield less carb intake.

Other Dietary Protocols

While every dietary protocol should stem from the fundamentals of energy balance (caloric surpluses or deficits) and macronutrient composition, there are a few dietary protocols worth mentioning here that you will need to be educated on.

Every dietary method should have a specific application, just like a tool in a toolbox is used for a specific purpose. You don’t simply use a screwdriver for everything that needs to be done and you shouldn’t be using a single dietary approach for every client that comes to you.

It is also important that you remain educated on current topics in the nutritional space. While you may not be a fan of their application, you must be willing to accurately discuss them with your clients and truly explain their benefits or lack thereof.

Ketogenic Diets

A keto diet (or a ketosis diet) is mostly known as a super low carb diet. A keto diet initiates weight loss in the body by producing ketones in the liver to be used as energy. Essentially the mechanism by which a keto diet works is that it deceives the body into thinking that it is fasting by a harsh removal of glucose found in carbohydrate food items. This is not accomplished through the starvation of calories but more the starvation of carbohydrates.

Imagine that you are a Toyota Prius and that carbohydrates are gasoline and fats are electric charge. Because you are a “hybrid” you will use the carbs for short bursts of activity and fats for slower, more prolonged activity. However, when all the gasoline (carbs) is used up your body must find energy from somewhere. It does this by breaking down fats in the liver and converting them to ketone bodies thus sending you to a state known as ketosis.

Possible Benefits of a Ketogenic Diet

There are numerous benefits from being on a keto diet. However, weight loss, controlling blood sugar levels and possible protection against cancers are three of the biggest.

Improved Weight Loss

When your body utilizes fat as an energy source there is obviously going to be some weight loss. Weight loss is a huge benefit of ketogenic diets due to lowered insulin levels (the fat storing hormone) and the body’s ability to burn stored fat.

Controlling Blood Sugar

A keto diet will logically decrease blood sugar levels due to the kind of foods you eat. Studies strongly show that ketogenic diets are an even more effective way to manage and prevent diabetes when comparing them to a calorie reduction diet.

Possible Protection against Cancer

One might ask “What is the connection between high-sugar diets and cancer?” Well, cancer feeds on sugar and sugar obviously comes from carbohydrates. Therefore, if you remove the sugar you can starve any cancer cells as the normal cells in our bodies can utilize fat as an energy source. However, it is strongly believed that cancer cells cannot make the metabolic transition from utilizing fat compared to glucose as a fuel source. Thus, a regime that removes processed carbs and sugars may be valuable in fighting or eliminating cancer.

Application of the Keto Diet

With the three benefits above it is clear to see that keto diets can and should absolutely be used with the right clients. These clients would include individuals that do not train, are purely seeking longevity, are severely overweight and/or pre-diabetic, or have or are at risk for cancer. Athletes competing in a sport that is purely aerobic may also benefit from a keto diet (marathoners, etc.).

However athletes competing in a sport that is highly central nervous system regulated and/or a sport that involves other energy system usage will NOT benefit from a ketogenic diet and will likely suffer several negative consequences. Remember that the nervous system’s preferred fuel source is carbohydrates and that our body can not create glucose from fats, therefore understanding the demands of your client’s training protocol is ESSENTIAL in determining proper application of a ketogenic protocol.

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