PRO Results Guide

Energy Balance

  • Description: average calories burned per day over the course of the test period (total energy expenditure [TEE]).

    Gold standard measurement

    Assumptions and Error Sources

    • Food quotient (proportions of fat, protein, and carbohydrate in the diet) is used to convert the rate of CO2 production to energy expenditure. If macronutrient data are not self-reported, a standard American diet is assumed (RQ = 0.86; approximately 45% fat, 16% protein, and 39% carbohydrate).

    Scientific Reference: Speakman et al. 2021

    Further Reading

  • Description: average calories absorbed per day over the course of the test period (total energy intake [TEI]).

    Formula: TEE +/- (Weight Change * Energy Content of Weight Change)

    • Gold standard method

    Assumptions and Error Sources

    • TEE is a gold standard measurement.

    • Weigh-in data are self-reported and input into a linear regression model to reduce artifacts of non-body weight changes (such as hydration, salt intake, glycogen stores).

    • An estimate of ~3,400 calories per pound of weight change is used based on available scientific research; actual energy content depends on the ratio of fat mass to lean body mass.

    Scientific Reference: de Jonge et al. 2007

    Further Reading

  • Description: daily difference between TEI and TEE.

    Formula: TEI - TEE

    Assumptions and Error Sources:

    • Both TEI and TEE are gold standard measurements/methods.

  • Description: weekly weight change associated with difference between TEI and TEE.

    Formula: (TEI - TEE) / (Energy Content of Weight Change)

    Assumptions and Error Sources

    • Both TEI and TEE are gold standard measurements/methods.

    • An estimate of ~3,400 calories per pound of weight change is used based on available scientific research; actual energy content depends on the ratio of fat mass to lean mass.

    Scientific Reference: de Jonge et al. 2007

  • Description: range of calorie intakes corresponding to common goals that represent “middle of the road” estimates based off of the scientific literature and general wellness recommendations.

    Formulas

    • Max Safe Fat Loss = TEE * 0.75

    • Burn Fat, Build Muscle = TEE * 0.90

    • Maintenance = TEE

    • Build Muscle = TEE * 1.10

    • Gain Weight = TEE * >1.10

    Assumptions and Error Sources

    • TEE is a gold standard measurement.

    Further Reading

Energy Budget

  • Description: multiple of BMRs burned over the course of the test period [PAL].

    Formula: TEE / BMR

    Assumptions and Error Sources

    • TEE is a gold standard measurement.

    • BMR is calculated using measured body composition, as well as age and sex.

    Further Reading

  • Descriptions

    • Basal Metabolic Rate (BMR): average calories burned per day at complete rest.

    • Thermic Effect of Food (TEF): average calories required per day to digest food.

    • Exercise: average calories exerted per day during logged workouts.

    • Non-Exercise Activity Thermogenesis (NEAT): average calories utilized per day by all other (non-exercise) activity.

    Formulas

    • BMR = Müller et al. 2004

    • TEF values = 15% for fat, 25% for protein, and 1.5% for carbohydrate

    • Exercise = none (self-reported)

    • NEAT = TEE - (BMR + TEF + Exercise)

    Assumptions and Error Sources

    • BMR is calculated using measured body composition as well as age and sex.

    • TEF is calculated using self-reported macronutrient data. If macronutrient data are not self-reported, a standard American diet is assumed (RQ = 0.86; approximately 45% fat, 16% protein, and 39% carbohydrate).

    • Exercise data are self-reported.

    • NEAT is estimated from gold standard measurement of TEE combined with calculated BMR, self-reported TEF, and self-reported exercise.

  • Description: the number of calories remaining (after accounting for exercise and training) relative to body size; measured as non-exercise calories eaten per kilogram of lean body mass [EA].

    Formula: (TEI - Exercise) / FFM

    Assumptions and Error Sources

    • TEI is a gold standard method.

    • Exercise data are self-reported.

    • FFM is a gold standard measurement.

    Scientific Reference: Melin et al. 2019

    Further Reading

  • Description: spectrum from completely sedentary (PAL of 1.1) to the maximum sustainable energy expenditure (PAL of 2.5); a result of less than 100% indicates sustainable training and a result of greater than 100% indicates overtraining. If greater than 100%, value is accompanied by the estimated training horizon (the number of days TEE is sustainable before the scientific literature predicts TEE will decrease, whether due to decreased training load, vacation, injury, sickness, etc.).

    Formula: (PAL - 1.1) / (2.5 - 1.1)

    Assumptions and Error Sources

    • PAL is estimated based on measured TEE and calculated BMR.

    Scientific Reference: Thurber et al. 2019

    Further Reading

Body Composition

  • Description: weight of all mass in body except for fat on day 1 of the test period (fat free mass [FFM]).

    Gold standard measurement

    Assumptions and Error Sources

    • Fat free mass is measured using deuterium dilution.

    • Hydration constant of 0.732 (the observed ratio of total body water to fat free body mass) is used to convert TBW to fat free mass.

    Scientific Reference: Melanson et al. 2018

  • Description: weight of fat mass in body on day 1 of the test period [FM].

    Formula: Weight - FFM

    Assumptions and Error Sources

    • Weight is self-reported.

    • FFM is a gold standard measurement.

  • Description: proportion of body weight that is fat on day 1 of the test period.

    Formula: FM / Weight

    Assumptions and Error Sources

    • FM is estimated based on reported weight and measured FFM.

    • Weight is self-reported and hydration status can affect body fat percentage measurements (if over-hydrated on day 1 of the test period, body fat percentage is likely under-estimated, whereas if you were under-hydrated, it is likely over-estimated.

Hydration

  • Description: average volume of water that flowed through the body each day over the course of the test period, including beverages, food, and metabolic water.

    Gold standard measurement

    Assumptions and Error Sources

    • Water throughput is measured using the dilution space of 2H dose and the rate at which 2H dose is measured to leave the body.

    Further Reading

  • Description: percentage of body weight that was comprised of water on day 1 of the test period [TBW].

    Gold standard measurement

    Assumptions and Error Sources

    • TBW is measured from the dilution space of the DLW dose. Dilution spaces of both 18O and 2H differ slightly from TBW by known values due to non-aqueous exchanges (18O dilution space is ~1% larger and 2H dilution space is ~4% larger).

    Scientific Reference: Speakman et al. 2021