BIObehavioral Health Systems Guide

This is a practical, science-based framework to help clients create sustainable fat loss and body

recomposition by aligning biology, behavior, and environment. It integrates the biomedical model

(physiology, metabolism, hormones), biobehavioral health science (how behavior interacts with

biology), and the Theory of Planned Behavior (how intentions become actions).

Why most plans fail: People often try to “out-discipline” physiology. Prolonged restriction, inconsistent

recovery, and non-progressive training increase metabolic adaptation and stress load, which can

reduce fat loss efficiency over time (Hall et al., 2022; Hackney, 2020). Sustainable outcomes require systems that are repeatable under real-life stressors (World Health Organization, 2023).

How to use this guide👇

Start with the Quick Start below for 7 days, then build the full system.

Quick Start: 7-day foundation

• Eat regularly (3–4 structured meals/day). Avoid compensatory fasting after indulgent days; it

increases rebound risk (Hall et al., 2022).

• Anchor protein at each meal to protect lean mass and metabolic rate (Phillips & Winett, 2021).

• Lift 2–4x/week with progressive overload to keep muscle as you lose fat (Phillips & Winett, 2021).

• Walk daily (10–30 minutes). Low-intensity movement supports glucose control and stress

regulation (Phillips & Winett, 2021).

• Protect sleep with consistent bedtime/wake time; sleep loss raises cortisol and appetite drive

(Hackney, 2020).

What “results” actually means

In this framework, results are measured in body composition, performance, energy, and

adherence—not just scale weight. A lower scale weight with muscle loss is not success. Preserving

lean mass supports long-term maintenance and metabolic health (Phillips & Winett, 2021).

Self-check: what’s most likely limiting you right now?👇

• Consistent hunger, fatigue, or cravings → energy availability and sleep/stress are likely too low (Hall

et al., 2022; Hackney, 2020).

• Plateau despite consistency → training stimulus and/or recovery may be insufficient; deficit may

have shrunk via adaptation (Hall et al., 2022).

• “On track” weekdays, chaos weekends → environment and TPB variables (norms + control) need strengthening (WHO, 2023; Ajzen, 2020).

👉🏻 If you want this to work long-term, stop treating nutrition and training like punishment. Treat them like inputs that regulate physiology.

The Biobehavioral Health Coach • @scarletfaithfit

System 1: Energy Availability & Metabolic

Regulation (Biomedical + Biobehavioral)👇

Core concept: When energy availability is chronically low, the body adapts by reducing energy expenditure and increasing stress physiology, which can make fat loss harder and adherence worse over time (Hall et al., 2022).

What metabolic adaptation can look like 👇

• Increased fatigue, lower training performance, more soreness that lingers (Hall et al., 2022).

• More hunger and cravings later in the day; “snap” decisions around food (Hall et al., 2022).

• Scale fluctuations and water retention during high stress/sleep loss (Hackney, 2020).

Why this happens (simple physiology)

Energy restriction reduces total energy expenditure through multiple pathways, including reductions in resting energy expenditure and adaptive changes in non-exercise activity. This can shrink the effective

deficit even when intake looks unchanged (Hall et al., 2022). At the same time, higher stress load can elevate cortisol, impair insulin sensitivity, and increase appetite drive—making “staying consistent” biologically harder (Hackney, 2020).

Implementation: a step-by-step system👇

• Step 1: Set a consistent meal structure (breakfast/lunch/dinner + optional snack). Structure reduces

decision fatigue and improves adherence (WHO, 2023).

• Step 2: Stop compensatory restriction after indulgent days. Return to baseline meals; compensation

increases rebound eating risk (Hall et al., 2022).

• Step 3: Fuel training days slightly higher than rest days to protect performance and adaptation (Hall

et al., 2022; Phillips & Winett, 2021).

• Step 4: Run a weekly check-in: energy, hunger, sleep, training performance, steps. Adjust one

variable at a time.

Practical example: “Back to baseline” day

Breakfast: protein + fiber + carbohydrate; Lunch: protein + produce + carbohydrate; Dinner: protein +

produce + carbohydrate; Snack (if needed): protein + fruit. This approach prioritizes satiety and stable

intake without punishment (Phillips & Winett, 2021; Hall et al., 2022).

Troubleshooting👇

• If you’re constantly hungry: check protein per meal and sleep debt first (Phillips & Winett, 2021;

Hackney, 2020).

• If performance is dropping: add fuel around training; low energy availability reduces adaptation

quality (Hall et al., 2022).

• If the scale jumps after holidays: assume water + glycogen + stress. Regulate sleep/stress and

return to baseline meals (Hackney, 2020).

The Biobehavioral Health Coach • @scarletfaithfit

System 2: Protein, Lean Mass, and Training

Signals👇

Core concept: Sustainable fat loss is easier when lean mass is protected. Protein intake and

resistance training help preserve fat-free mass and support metabolic rate during weight loss (Phillips

& Winett, 2021).

Why lean mass matters after 30 (and always)

Lean mass supports resting energy expenditure and insulin sensitivity. When clients lose weight

without protecting muscle, they often feel “smaller” but not leaner, and maintenance becomes harder.

Protein plus progressive resistance training improves body composition outcomes (Phillips & Winett,

2021).

Protein strategy (behavior + biology)👇

• Step 1: Protein at every meal. This improves satiety and supports muscle retention (Phillips &

Winett, 2021).

• Step 2: Distribute protein across the day (not all at dinner). Consistent dosing supports muscle

protein remodeling (Phillips & Winett, 2021).

• Step 3: Pair protein with fiber-rich produce for appetite stability and meal satisfaction (WHO, 2023).

Training strategy: the progressive overload checklist👇

• Step 1: Train 2–4 days/week minimum. Consistency beats intensity (WHO, 2023).

• Step 2: Track 1–2 key lifts per pattern (squat/hinge/push/pull). Add reps or load over time (Phillips &

Winett, 2021).

• Step 3: Avoid replacing lifting with excessive cardio when stalled; protect muscle first (Phillips &

Winett, 2021).

• Step 4: Keep daily steps moderate and repeatable; it supports energy expenditure without

compromising recovery (Hall et al., 2022).

Sample week (simple, repeatable)

2–4 lift days: full-body or upper/lower split. Daily: 20–40 minutes total walking/steps as tolerated.

Nutrition: protein at each meal; slightly higher fuel on training days to preserve output (Phillips & Winett,

2021; Hall et al., 2022).

Common mistake: chasing scale weight over signal quality

When clients cut too aggressively, training quality drops, NEAT often drops, and the deficit shrinks via

adaptation (Hall et al., 2022). The fix is almost always improving signal quality: protein, training

progression, and recovery (Phillips & Winett, 2021).

The Biobehavioral Health Coach • @scarletfaithfit

System 3: Stress, Sleep, and the Theory of

Planned Behavior👇

Core concept: Stress and sleep are not “mindset topics”—they are physiological variables. Sleep loss

and chronic stress elevate cortisol and impair insulin sensitivity, which can increase hunger, fatigue,

and fat retention (Hackney, 2020).

TPB: why you can ‘know what to do’ and still struggle👇

The Theory of Planned Behavior explains that actions are driven by intention, and intention is shaped

by: attitude (beliefs about the behavior), subjective norms (what feels normal socially), and

perceived behavioral control (confidence you can do it) (Ajzen, 2020). Stress and sleep debt reduce

perceived control by impairing self-regulation capacity (Hackney, 2020).

Stress & sleep: what to do this week👇

• Step 1: Set a consistent sleep window (same wake time most days). This improves recovery

signaling (Hackney, 2020).

• Step 2: Build a 10-minute downshift routine (light stretch, shower, reading). Routine strengthens adherence systems (WHO, 2023).

• Step 3: Use low-intensity movement as regulation (walk after meals). Supports glucose regulation and stress reduction (Hackney, 2020; Phillips & Winett, 2021).

Theory Planned Behavior Coaching 👇

• Attitude: Replace “I have to be perfect” with “I’m building repeatable signals.” Perfection increases

stress load (Hackney, 2020).

• Norms: Create supportive defaults (protein prepped, planned workouts). Environments drive

adherence (WHO, 2023).

• Control: Shrink the plan until it feels doable on your hardest day. Perceived control predicts

follow-through (Ajzen, 2020).

When ‘the scale is up’ after stressful weeks

High cortisol + poor sleep can increase water retention and appetite drive (Hackney, 2020). The correct response is not restriction. Return to baseline meals, walk, lift, and prioritize sleep for 3–5 days before changing calories (Hall et al., 2022; Hackney, 2020).

The Biobehavioral Health Coach • @scarletfaithfit

System 4: Behavior Systems, Plateaus, and

Maintenance👇

Core concept: Motivation is volatile. Systems are stable. Sustainable change requires routines,

feedback loops, and environmental design (World Health Organization, 2023).

Your weekly feedback loop (10 minutes)

• Step 1: Track trends: 7-day average weight (optional), waist/hip measurements, training

performance, steps, sleep.

• Step 2: Identify the constraint: fuel, training stimulus, recovery, or environment.

• Step 3: Adjust one variable for 7–14 days (e.g., add fuel around training; increase progression;

improve sleep routine).

Plateau decision tree (simple)👇

• If performance is down + hunger is up: increase energy availability and sleep; adaptation is likely

(Hall et al., 2022; Hackney, 2020).

• If performance is stable but no body change: progress training and confirm consistent meal

structure (Phillips & Winett, 2021; WHO, 2023).

• If weekends derail you: strengthen norms and control—plan social meals, prep protein, schedule training (Ajzen, 2020; WHO, 2023).

Maintenance is a skill (not a phase you ‘earn’)

Maintenance requires the same systems: adequate protein, consistent training stimulus, regulated sleep/stress, and repeatable routines (Phillips & Winett, 2021; Hackney, 2020; WHO, 2023). The biomedical goal is stable energy availability with enough stimulus to preserve lean mass (Hall et al.,

2022).

Action plan worksheet (write your answers)👇

• My easiest daily anchor: ___________________________

• My biggest barrier (fuel/training/recovery/environment): ___________________________

• One change I will run for 14 days: ___________________________

• How I will measure progress (performance/measurements/energy):

___________________________

References:

Hall, K. D., et al. (2022). Metabolic adaptation to energy restriction and implications for weight loss. Phillips, S. M.,

& Winett, R. A. (2021). Protein intake, resistance training, and lean mass retention during weight loss. Hackney,

A. C. (2020). Stress physiology (cortisol) and implications for metabolism and fat regulation. Ajzen, I. (2020).

Theory of Planned Behavior: contemporary applications. World Health Organization. (2023). Social and

biobehavioral determinants of health and obesity.

The Biobehavioral Health Coach • @scarletfaithfit

Questions__email: teamscarletfit@gmail.com

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