Glossary
Clear definitions for every metric
Short, practical explanations for the terms you see in Fuel.
Body Composition is the ratio of fat mass to fat-free mass, and understanding trend direction matters more than point precision for most programs..
Body Fat Percentage estimates body composition as a percentage, not a medical diagnosis and not an unbroken truth.
Fat-Free Mass includes lean tissue and water compartments excluding fat mass.
Lean Mass is the non-fat fraction that is responsive to nutrition, hydration, inflammation, and training.
A balanced diet provides enough protein, carbs, fats, fiber, and micronutrients to match your energy needs and support health and performance.
Carb Cycling places carbohydrate load around demands while preserving weekly energy alignment..
Glycemic index (GI) ranks carbohydrate foods by how quickly they raise blood glucose in standardized testing.
Glycemic Load combines carbohydrate quality and portion size into a practical planning number for timing and repeatability..
Intermittent fasting is a timing framework for energy intake, not a stand-alone recovery or fat-loss shortcut..
Meal replacements can be a practical fallback when cooking time is constrained, but most plans work best when they supplement (not replace) whole foods..
Nutrient density compares vitamins and minerals to calories, helping you meet micronutrient needs within a calorie budget..
Nutrient Timing schedules meals around activity to support performance and recovery..
Protein timing is how you spread protein across the day to support recovery and muscle growth.
A refeed day temporarily raises calories (often via carbs) during fat loss to support training and adherence..
The satiety index ranks foods by how filling they are per calorie; use it as a clue, not a rule, because meals matter more than single foods..
Food Allergy Tracking logs exposure and reaction timing, then separates probable allergy patterns from noise..
Food intolerance is a dose-dependent digestive response, while allergy includes immune signaling.
Many users report symptoms after gluten exposure, but the underlying cause is often not one pattern.
Lactose Intolerance is a digestion limit, and tolerance is often tied to total dose and timing..
Plant-based proteins can meet intake goals when amino-acid gaps and timing are handled intentionally..
Barcode Scanning pulls packaged food data into your logs quickly, then flags mismatches before macro decisions are locked..
A food database stores nutrition entries for quick search and logging.
Food Diary records what you eat and drink so nutrition pattern becomes visible..
Food logging gives measurable data for energy and behavior, while the method stays simple enough to sustain..
Food scales improve accuracy for portions and recipes, especially when meal components vary and you want consistent macro totals.
Macro Tracking turns food entries into trend data, not just one-off meal perfection..
Photo Logging captures quick evidence and supports pattern checks when text input is slow..
Voice logging captures meals by speech for speed, then converts them into structured food entries..
Blood sugar control means reducing extreme swings while preserving performance.
A continuous glucose monitor (CGM) is a small wearable device that tracks your glucose levels around the clock, offering a window into how your body responds to everything from your morning coffee to your evening workout.
Step Count tracks daily movement and offers a practical signal for non-exercise activity, but accuracy depends on device placement, context, and behavior pattern..
Wearable metrics capture activity and recovery data that inform daily plans.
Electrolyte Balance supports nerve signaling, muscle contraction, and fluid distribution.
Hydration supports blood volume, temperature control, and performance.
Sodium supports fluid balance, nerve communication, and exercise performance..
Water Intake Goals aim to keep hydration steady across daily life and training.
Mindful Eating means paying attention to hunger, appetite, and satisfaction signals..
Sleep hygiene is the set of behaviors and environment choices that make solid sleep more likely..
Sleep tracking records duration and quality signals so recovery plans are based on trends, not single-night noise..
Stress management reduces mental and physical strain so recovery and decision quality improve.
The 4-4-9 rule is the calorie accounting baseline where protein and carbohydrate contribute 4 kcal per gram and fat contributes 9 kcal per gram, used to transform food grammage into a workable energy framework..
Carbs differ most in fiber density and digestion speed.
Cholesterol is a biological substrate for hormone and membrane function, and blood levels reflect diet, genetics, and training context..
Complex carbs pair with fiber and structure.
Dietary fat supports satiety, hormone synthesis, and training consistency when placed in the right range for your phase..
Fiber supports digestion, satiety, and blood pattern stability..
Omega-3s include EPA and DHA from marine foods and ALA from plants, with different conversion and impact paths..
Protein Quality describes how complete and available a protein source is for tissue repair and immune support, not just its total gram value..
Saturated Fat is often framed as “always bad,” but a context-based framework is more useful..
Simple carbs digest quickly and can raise blood sugar faster than complex carbs.
Unsaturated Fat includes monounsaturated and polyunsaturated fats, with Saturated Fat tracked separately..
Bulk cooking is a force multiplier for adherence because it reduces daily decision load while preserving plan quality..
A Grocery List is a planning tool, not a random basket, so each buy cycle should align with training phase and expected prep rhythm..
Macro-friendly recipes provide predictable per-serving values so you can hit targets with less guesswork..
Meal Frequency is a scheduling choice for consistent protein and energy distribution, not a rigid rule..
Meal Planning maps your targets to meals you will actually eat..
Meal Prep turns meal planning into a controlled execution loop with fewer daily choices..
Meal prep containers keep food portions stable, reduce waste, and make it easier to repeat meals that fit your plan..
Meal suggestions combine remaining macros, timing, and schedule reality to keep choices practical..
Portion control keeps meals aligned with your targets without weighing every ingredient.
A serving size is the reference amount on a label; your actual portion can be different.
Active Calories describe the energy used when you move above a resting state.
Basal Metabolic Rate (BMR) is the baseline energy your body uses for core cellular maintenance at rest.
Calorie Burn Estimation splits estimated energy into fixed and variable parts, then tests assumptions against trend data..
Non-Exercise Activity Thermogenesis (NEAT) is energy from daily movement outside planned workouts..
Resting Metabolic Rate (RMR) is the energy burned at rest while awake in a relaxed state and is interpreted alongside Heart Rate Zones to keep estimates realistic..
Total Daily Energy Expenditure (TDEE) is the sum of calories you burn each day..
Adaptive Calorie Goals adjust daily intake targets from a rolling evidence loop.
Calorie Targets convert maintenance logic into objective-specific intake targets..
A macro budget is a weekly spending plan for protein, carbohydrate, and fat around your calorie and training objective..
Macro ratios describe how your calories split between protein, carbs, and fat.
Macro suggestions are context-based adjustments to your day-level macro plan, not a one-size template.
A macronutrient profile shows how your daily calories split across protein, carbs, and fat.
Macros by meal distribute your daily targets across meal slots so totals stay steady even on busy days.
Personalized macro targets size protein, carbs, and fat for your goal, body size, training, and schedule.
Adaptive Learning updates recommendations as new behavioral and physiologic signals arrive, then recalibrates output to reduce the gap between expected and observed outcomes..
AI Coach gives data-aware coaching for habits, calories, and macro execution.
AI Diet Planning builds meals by combining goals, constraints, and behavioral context into a reliable weekly plan..
The AI Recipe Generator creates recipes that match your dietary constraints, rhythm, and pantry reality while staying near your targets..
Chatbot Feedback handles adherence, appetite, and stress questions with scenario logic and explicit confidence tags..
Progress Visualization turns logs into charts so you can act with confidence..
Trend analysis smooths noisy data so changes are based on patterns, not single days..
A Deload Week reduces load for a short period and is most effective when timing is based on objective signals..
Heart rate zones group intensity into bands so cardio sessions are repeatable and fatigue is easier to manage..
Interval training alternates focused work and recovery blocks to build fitness efficiently without turning every session into a grind..
Post‑Workout Nutrition supports repair and glycogen replenishment, especially when paired with Pre-Workout Nutrition..
Pre-workout nutrition is about fueling your body strategically before exercise to maximize performance while avoiding digestive discomfort.
Progressive overload increases training stress gradually to drive adaptation, while recovery sets the pace of progress..
Recovery time is how long your body needs before repeating hard work at the same intensity and quality..
A training split organizes sessions across the week so volume, intensity, and recovery are distributed on purpose..
B vitamins function as coenzymes across energy conversion, methylation, and redox control.
Calcium acts as a structural and signaling mineral at the same time.
Iron status affects oxygen transport and can influence energy, endurance, and training recovery.
Magnesium supports neuromuscular, energy, and recovery systems through multiple cellular roles..
Micronutrients are nutrients required in small absolute quantities but essential for metabolic continuity, cellular signaling, and recovery.
Potassium helps maintain fluid balance and supports muscle and nerve function, working with sodium intake as part of overall electrolyte balance..
Supplements can be useful when food intake, schedule variability, and recovery demands create persistent gaps in key nutrients.
Vitamin D is both hormone precursor and signaling regulator.
A Calorie Deficit occurs when intake is lower than daily expenditure, producing weight loss over time..
A calorie surplus supports tissue gain only when excess is controlled.
GLP-1 (glucagon-like peptide-1) is a hormone your gut produces naturally to help manage hunger and blood sugar after meals.
A GLP-1 receptor agonist is a prescription medication that works by mimicking a hormone your body naturally produces after eating.
Liraglutide is a GLP-1 receptor agonist medication that helps manage blood sugar and weight, depending on which version you're prescribed.
Maintenance Calories are the intake that keeps body weight stable over time..
Mounjaro is the brand name for tirzepatide, a medication that works by activating two hormone pathways (GIP and GLP-1 receptors) to help control blood sugar and reduce appetite.
Ozempic is a brand name for semaglutide, a GLP-1 receptor agonist medication.
Retatrutide is an experimental weight management medication currently being studied in clinical trials.
Reverse dieting is a staged increase in intake after a deficit so training quality and hunger stabilize while weight regain stays controlled..
Rybelsus is the daily tablet version of semaglutide, a GLP-1 receptor agonist that helps control appetite and blood sugar.
Saxenda is a prescription medication containing liraglutide, which belongs to a class of drugs called GLP-1 receptor agonists.
Semaglutide is a GLP-1 receptor agonist medication that helps control appetite and blood sugar levels.
Tirzepatide is a medication that works by activating two hormone receptors in your body—GIP and GLP-1—which naturally help regulate blood sugar and appetite.
Victoza is the brand name for liraglutide, a medication that belongs to the GLP-1 receptor agonist family.
Wegovy is a prescription medication containing semaglutide, a GLP-1 receptor agonist designed to help with weight management.
A weight loss plateau is a 2+ week period with no downward trend despite consistent effort..
Zepbound is the brand name for tirzepatide, a medication that works by activating two hormone receptors (GIP and GLP-1) to help control appetite and blood sugar.