What Is Calculated, What Is Guided, & What Is Still An Estimate.

Energy & Activity

Resting energy uses Cunningham when a usable body-fat estimate is supplied and Mifflin–St Jeor otherwise. Explicit training uses net MET energy above rest, then remains separate from the non-exercise lifestyle multiplier to reduce double counting.

• Cunningham Resting-Energy Equation
• Mifflin–St Jeor Equation
• Compendium Of Physical Activities
• NIDDK Body Weight Planner — dynamic change model and limits of simple calorie rules

Automatic Age Routing

Ages 13–18 use the 2023 National Academies youth Estimated Energy Requirement equations, which include age, sex, height, weight, activity category, and energy for growth. Logged exercise is shown as context and is not added again. Ages 19–65 use the standard adult pathway; ages 66–78 retain the adult estimate with added uncertainty language; age 79 and above is explicitly marked as an extrapolation beyond the original Mifflin–St Jeor sample.

• 2023 Dietary Reference Intakes For Energy — Youth And Adult Equations
• Mifflin–St Jeor Derivation Population, Ages 19–78

Weight-Loss Pace & Clinical Territory

Standard planning stops at 1% of current body weight per week. Faster choices are visible only under clinician-supervised context with a configurable minimum-intake floor. A medication or a higher starting weight does not independently certify a rapid rate as safe.

• CDC Gradual Weight-Loss Guidance
• NIH/Endotext Obesity Dietary Treatment
• ADA Standards Of Care In Diabetes—2026
• NIDDK Prescription Weight-Management Medicines

Very Low Body Fat & Energy Availability

The new competitor images are visual references, not recommended targets. Very-low body fat and inadequate energy availability can compromise reproductive function, bone health, recovery, mood, immunity, and performance in women and men.

• IOC REDs Consensus Statement (2023)
• ACSM Female Athlete Triad Position Stand

Build, Cut, & Body-Fat Coaching

The 12% male and 26% female build cautions are deliberately presented as tough-love coaching triggers—not universal physiological thresholds. Evidence supports slower loss for leaner athletes and controlled surpluses, but does not establish one body-fat percentage at which every person must or must not build.

• ISSN Position Stand On Diets And Body Composition

Macros, Fiber, & Hydration

Protein is set from body weight and lean mass before calories are allocated to fat and carbohydrate. Fiber uses the 14 g per 1,000 kcal DRI as a reference but applies a practical display range. Water is a planning estimate translated into liters, ounces, gallons, and the selected bottle size.

• Dietary Reference Intakes For Fiber And Water
• ACSM Exercise And Fluid-Replacement Position Stand

Calibrate Against Reality

Body-fat visuals, calipers, METs, stride length, wearable calories, and weekly energy conversion all carry error. Use consistent measurement conditions and several weeks of weight, waist, performance, hunger, recovery, and adherence trends. Seek clinical guidance for pregnancy, eating-disorder history, medications, kidney or heart disease, bariatric care, or aggressive loss.

Method Ledger Last Reviewed: August 2026.