What is 'doubly labeled water' and how is it used to measure energy expenditure?

Doubly labeled water is considered the gold standard for measuring total daily energy expenditure in free-living individuals. It involves enriching body water with heavy isotopes of oxygen and hydrogen, then measuring the difference in their washout kinetics from urine samples to estimate carbon dioxide production and, consequently, energy expenditure.

Do men and women have different metabolic rates?

The research by Pontzer et al. suggests that males and females have pretty similar energy expenditure when differences in body composition, particularly fat-free mass, are accounted for. The main variability comes down to tissue mass, not biological sex directly.

How can I accurately estimate my total daily energy expenditure (TDEE) for dieting?

You can start with a crude estimate (14-16 kcal/lb body weight), or use validated equations like the Cunningham equation combined with activity multipliers. For best accuracy, consistently monitor your daily weight and caloric intake over time and use that data to individually titrate your TDEE.

What are the common criticisms of traditional activity multipliers for TDEE estimation?

Traditional activity multipliers often use broad categories (sedentary, moderately active, etc.) that don't accurately reflect modern lifestyles where people might have sedentary jobs but intense daily exercise. This can lead to confusion and poor TDEE estimates, as external activity is uncoupled from gym activity.

Does blood flow restriction (BFR) training cause muscle damage?

A systematic review indicates that BFR training can cause substantial muscle damage if performed to failure. However, non-failure BFR protocols (like the 30-15-15-15 method) tend to promote hypertrophy with minimal or no significant muscle damage.

Is blood flow restriction (BFR) training good or bad for vascular health?

A systematic review and meta-analysis found that BFR training has similar positive effects on vascular structure compared to conventional training, and may even have larger positive effects on vascular function. Initial concerns about negative impacts due to disrupted shear stress were not supported.

What is Turkesterone and is it an effective supplement for muscle growth?

Turkesterone is a phytoecdysteroid, a compound from plants. While some in vitro and rodent studies show promising anabolic effects and it's popular in the supplement world, there is currently no relevant human literature to confidently conclude it's an effective ergogenic aid for muscle growth or performance.

Why is it important to increase or maintain fat-free mass as we age?

Beyond age 60, fat-free mass tends to decrease, contributing to a drop in total daily energy expenditure. Prioritizing training and nutrition to maintain or build fat-free mass can help to delay sarcopenia and support successful aging, offsetting some of the age-related decline in metabolic rate.

What are some simple meatless meal ideas for high-protein diets?

Lentil soup is highlighted as an inexpensive, easy-to-make, and very nice protein source for bulk cooking. Asian-inspired stir-fries with tofu and various Asian sauces are also recommended as super easy, well-balanced, high-protein, and vegetable-rich options.

Key Moments

Metabolic Rate, Blood Flow Restricted Training, and Turkesterone (Episode 63)

Stronger By Science

Sports4 min read106 min video

Aug 26, 2021|6,510 views|215|19

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Key Moments

TL;DR

Podcast discusses metabolic rate, BFR training, and Turkesterone, plus strategies for estimating energy expenditure.

Key Insights

Energy expenditure remains stable from ages 20-60 when accounting for body composition, contrary to popular belief.

Beyond age 60, energy expenditure declines primarily due to loss of fat-free mass, not significant fat gain.

Blood flow restriction (BFR) training can induce muscle hypertrophy without significant muscle damage if not taken to failure.

Turkesterone's efficacy as a performance-enhancing supplement lacks sufficient human trial evidence.

Estimating total daily energy expenditure can be done through simple formulas, equations with multipliers, or by observing intake and weight changes.

Maintaining fat-free mass and activity levels is crucial for successful aging beyond 60.

SEASON 5 AND MACROFACTOR APP ANNOUNCEMENT

The Stronger By Science podcast returns for Season 5 after a summer break, featuring hosts Eric Trexler and Greg Nuckols. They announce an upcoming live Q&A episode on September 2nd, encouraging listeners to submit questions. The overarching goal for the coming weeks is content surrounding the impending release of their nutrition app, MacroFactor, with a target launch in mid-September. This content push aims to keep the audience engaged with articles and other materials leading up to the app's release.

RESEARCH REVIEW: AGE, SEX, AND ENERGY EXPENDITURE

A significant portion of the episode is dedicated to a large-scale study by Ponzar et al. on daily energy expenditure across the human lifespan. This international collaboration, utilizing the doubly labeled water database, analyzed data from over 6,400 participants. Key findings indicate that energy expenditure is stable from ages 20 to 60 when adjusted for body composition, challenging common assumptions about metabolic slowdown in adulthood. The study also found similar energy expenditure between males and females after accounting for body composition.

ENERGY EXPENDITURE CHANGES WITH AGING

The research also explored energy expenditure beyond age 60, noting a decline primarily linked to a reduction in fat-free mass rather than an increase in fat mass. While overall expenditure decreases, researchers pointed to potential contributing factors such as lower activity levels and a decline in organ-level metabolic rates. This contradicts the notion of inevitable rapid fat gain post-60 due to a drastically slowed metabolism.

PRACTICAL STRATEGIES FOR ESTIMATING ENERGY EXPENDITURE

To help listeners estimate their Total Daily Energy Expenditure (TDEE), the hosts outlined several methods. The simplest is a rough calculation based on body weight (14-16 kcal/lb or 30.8-35.2 kcal/kg). A more refined approach involves using validated equations like Mifflin-St Jeor or Cunningham to estimate Resting Energy Expenditure, then applying a physical activity multiplier. They proposed a more nuanced multiplier that separates general activity from structured exercise. The most accurate method involves consistent observation: tracking caloric intake and body weight changes over time.

RESEARCH UPDATE: BLOOD FLOW RESTRICTED TRAINING (BFR)

Greg provides an update on Blood Flow Restriction (BFR) training, specifically addressing its effect on muscle damage. While early research suggested minimal muscle damage, recent systematic reviews indicate that training to failure with BFR can lead to significant muscle damage and soreness. However, BFR protocols that avoid failure, like the 30/15 method, still promote hypertrophy and strength gains with much lower markers of muscle damage. Another review suggests BFR training has similar or even potentially better effects on vascular function compared to conventional resistance training.

SUPPLEMENT SPOTLIGHT: TURKESTERONE

The hosts discuss Turkesterone, a phytoecdysteroid, in response to frequent listener questions. Despite its growing popularity, they found a notable lack of robust human trial data supporting its efficacy for performance enhancement. While in-vitro and rodent studies exist, they emphasize the need for high-quality human research to confirm claims regarding anabolic or hypertrophy-inducing effects. They stress that the dose consistency and bioavailability of such supplements are often questionable, putting the burden of proof on manufacturers.

COACH'S CORNER: DIETING STRATEGIES AND INDIVIDUALIZATION

Building on the energy expenditure discussion, Eric emphasizes the importance of TDEE estimation for diet planning. He cautions against setting universal calorie limits, stressing that individual energy expenditure varies significantly, even with similar body composition. He highlights that simply applying population-level equations can be insufficient, and consistent monitoring of weight and intake is crucial for accurate individual TDEE assessment, a concept central to their MacroFactor app development.

FOOD SEGMENT: SCOTCHETTI AND HOT POCKETS

The episode concludes with a food segment. Greg plans to make Scochetti, an Italian dish described as 'lasagna bread,' highlighting its layered dough and versatile fillings. Eric humorously plans to bring a 'perfectly cooked' Hot Pocket, emphasizing a unique cooking method that preserves a frozen core for a distinct texture and temperature contrast, contrasting with traditional preparation methods.

Mentioned in This Episode

●Supplements

●Software & Apps

●Tools

●Companies

●Organizations

●Books

●Studies Cited

●Concepts

●People Referenced

Estimating Total Daily Energy Expenditure (TDEE)

Practical takeaways from this episode

Do This

Asssume TDEE starting at 14-16 kcal/pound (30.8-35.2 kcal/kg) for a crude estimate.

Use validated equations like Cunningham (especially for lifters) to estimate resting energy expenditure.

Apply customized activity multipliers: 1.2 (inactive), 1.4 (moderately active), 1.6 (really active) for general activity, plus 0.0-0.3 for structured exercise sessions.

Accurately monitor daily weight in a standardized way (morning, minimal clothing, after restroom, no food/drink).

Accurately monitor daily caloric intake if it doesn't cause psychological distress.

Triangulate monitored weight and calorie intake data over time for a precise TDEE estimate.

Avoid This

Do not make broad, universal statements about minimum calorie intake limits; individual needs vary.

Avoid relying solely on generic activity multipliers that don't differentiate between general physical activity and structured exercise.

Do not over-interpret day-to-day fluctuations in water weight when assessing progress.

Do not pursue unproven supplements like Turkesterone without robust human clinical trials showing efficacy, safety, and bioavailability.

Organ-Specific Metabolic Rates by Age Group (kcal/kg/day)

Data extracted from this episode

Organ	Age 21-30	Age 51-73
Liver	~200	~200
Brain	242	233
Heart/Kidneys	443	426
Skeletal Muscle	13	13

MacroFactor Activity Multiplier Categories

Data extracted from this episode

General Activity Level	Multiplier	Training Sessions per Week	Additional Multiplier
Inactive/Sedentary	1.2	0	0.0
Moderately Active	1.4	1-3	0.1
Really Active (high NEAT)	1.6	4-6	0.2
N/A	N/A	7+	0.3

Common Questions

A large international study found that when accounting for body composition, energy expenditure remains relatively stable from age 20 to 60. After age 60, basal metabolic rate and total daily energy expenditure tend to drop, primarily due to decreases in fat-free mass and slight declines in organ-level metabolic rates, not necessarily increased fat gain.