This blog covers nutrition-related math, particularly as it relates to caloric balance (calories in vs calories out) is an important concept. If we have a caloric surplus, this will result in weight gain. If we have a caloric deficit, there will be weight loss. As exercise professionals, we can teach clients how to keep track of their caloric intake, estimate their caloric needs and read food labels. This blog covers the nutrition-related math that may be on the exam, including nutrition labels, caloric deficits and macronutrient needs based on caloric intake.
First, I want to address the difference between a Calorie and a Kilocalorie: There is none! While a calorie (not the lowercase c) is a very small unit of measurement, Calories (with a capital C) is 1,000 calories. Otherwise, every value on a nutrition label would be multiplied by 1,000. Can you imagine how challenging it would be to understand a nutrition label if a typical recommended daily intake was 2 million instead of 2,000 calories per day? For the purposes of nutrition, whenever you see Calories, know that a Kilocalorie and a Calorie are the same thing.
Let’s start with the nutrition label as this can be an area of confusion for the general population. Important concepts include serving size vs. servings per container and percent of calories coming from fat, protein or carbs. Many people mistakenly believe that the nutrition facts are describing the whole package, but it’s just one serving. Also, it’s important to look at the breakdown of calorie content to determine what types of nutrients are in a given food. Here are some examples:
Determining Calories per Serving and Calories from Fat, Protein and Carbohydrates:
Determine Total Number of Calories per Package:
- Determine Calories Per Package
- Locate Calories per serving and multiply by the number of servings. In this case, there is only one serving, so the number of calories is the same as the number of calories in the package. However, that is not always the case so help your clients be aware.
Determine Percentage of Calories from Protein, Fat, and Carbohydrate:
- Determine Percentage of Calories from Fat
- Hint: Often they will list the Calories coming from fat right next to where they list the Calories per Serving.
- If they do not give you that information, then you multiply the number of fat grams by 9 (9 Calories per gram).
- 5 g x 9 Cals/gram= 45 Calories from fat
- Divide Calories coming from fat by TOTAL Calories
- 45/232= .1939655 or 19.39655%
- There is ~19.4% of calories coming from fat
- Determine Percentage of Calories from Carbohydrate
- Multiply the number of grams coming from Total Carbohydrate by 4
- 26 g x 4 Cals/gram = 104 Calories of Carbohydrates
- Divide the number of Calories coming from Total Carbohydrate by the Total Calories
- 104/232 = .4482758 or 44.82758%
- There is ~44.8 % of Calories coming from carbohydrates
- Determine Percentage of Calories from Protein
- Multiply the number of grams from protein by 4
- 20 g x 4 Cals/gram = 80 Calories from protein
- Divide the total number of Calories coming from Protein by Total Calories
- 80/232= .3448275 or 34.48275%
- There is ~34.5% of Calories coming from protein
- Note: There may be a discrepancy between the number of calories listed and the number that we get when we total up the calories coming from each of the three macronutrients. In this example, the total calories are 232, but if we add the calories we get from each macronutrient, we get 229 (45 fat + 104 carbs + 80 protein). This is because typically the grams are rounded to the nearest 0.5 gram so there might be 4.9 or 5.1 grams of fat, but instead they round it to 5 grams. Also, if the food contains less than 0.5 grams/serving it doesn’t have to be included on the nutrition label. The discrepancies will always be very minute, so don’t worry about that for exam day. It’s just something you and your clients should be aware of when reviewing a nutrition label.
Determining Macronutrient Needs:
Let’s consider a person on the average 2,000 Calorie/Day diet for the next few examples.
Determine Carbohydrate Needs Based on % Calorie Diet
- It’s recommended that 45-65% of calories come from carbohydrate sources, so multiply 2,000 (or whatever their Calorie needs are) by 45% and 65% to get an acceptable Calorie Range
- 2000 x 0.45 = 900
- 2000 x 0.65 = 1300
- This person would want to consume 900-1300 Calories per day of carbohydrate
- To determine the number of grams, divide these values by 4
- 900/4 = 225 grams
- 1300/4 = 325 grams
- A person consuming a 2,000 Calorie Diet will want to consume 225-325 grams of carbohydrate
Determine Fat Needs Based on % Calorie Diet
- It’s recommended that 20-35% of calories come from fat sources, so we will multiply 2,000 (or whatever their Calorie needs are) by 20% and 35% to get an acceptable Calorie Range
- 2000 x 0.20 = 400 Calories
- 2000 x 0.35 = 700 Calories
- This person would want to consume 400-700 Calories per day of healthy fats
- To determine the number of grams divide each number by 9
- 400 Calories/9 = 44.444444 grams
- 700/9 = 77.77777 grams
- A person consuming a 2000 Calorie Diet will want to consume ~44.4 and 77.8 grams of healthy fat
Determine Protein Needs Based on % Calorie Diet
- It’s recommended that 10-35% of calories come from protein sources, so we will multiply 2,000 (or whatever their Calorie needs are) by 10% and 35% to get an acceptable Calorie Range
- 2000 x 0.10 = 200 Calories
- 2000 x 0.35 = 700 Calories
- This person would want to consume 200-700 Calories per day of protein
- To determine the number of grams divide these values by 4
- 200/4 = 50 grams
- 700/4 = 175 grams
- A person consuming a 2000 Calorie Diet will want to consume 50-175 grams of protein
Determine Protein Needs Based on Activity Level
- Activity levels can give us a more individualized idea of how much protein a person should consume. A moderately active person (your average person) needs a minimum of 0.8 grams per kilogram of body weight. Those who train strenuously for strength or endurance (i.e., athletes or people training 5-7 days/week) need more within the range of 1.2-1.7 grams of protein per kilogram of body weight. Let’s calculate both for a 200-pound male who attends the gym three times a week for 60 minutes (average protein requirements). We’ll also calculate the protein needs of the same man if they were training more than two hours per day, six days a week, for an upcoming Olympic lifting competition
- Average Protein Needs: 0.8 g/kg body weight
- Determine weight in kilograms: 200/2.2 = 90.9 g
- Multiply weight in kg by 0.8: 90.9 x 0.8: = 72.727272 g
- This person would want to consume a minimum of 72.7 grams of protein per day
- Strength or Endurance Athlete Protein Needs: 1.2-1.7 g/kg body weight
- Determine weight in kilograms: 200/2.2 = ~90.9 g
- Multiply weight in kilograms by 1.2 and 1.7 to create an appropriate range: 90.9 x 1.2 = 109.8 and 90.9 x 1.7 = 154.5
- This person would want to consume 109-154 grams of protein per day.
Determining Caloric Deficit Needed for Desired Weight Loss
There are 3,500 calories in 1 pound, so to help a client lose weight we need to determine the TOTAL caloric deficit needed and the TIME FRAME in which to create that deficit (first make sure that it is within that healthy weight loss range of one to two pounds per week, of course). Consider the following example: Your new client is a male whose spouse is away for a few months for work. He wants to surprise her by losing the 15 pounds he has put on over the last few years. He has exactly 12 weeks to lose the weight, so what is the daily caloric deficit needed to achieve this goal?
Step 1: Determine Total Caloric Deficit Needed for 15 Pounds of Fat Loss
3,500 x 15 = 52,500
Step 2: Determine Total Number of Days to Lose Weight
12 weeks x 7 Days = 84 Days
Step 3: Divide Total Caloric Deficit Needed by Total Number of Days to Lose Weight
52,500/84 = 625 of Caloric Deficit needed per day
NOTE: A caloric deficit can be created through physical activity and caloric restrictions. Ideally, we want to use a combination of both to achieve this caloric deficit, making sure not to restrict the client’s diet too much that it puts him below his Basal Metabolic Rate, which can adversely affect his metabolism. When the body isn’t getting enough fuel, it will decrease its metabolic rate to more closely match the intake, which is why mild caloric restriction is preferred.