Sources & Methodology

Fignal estimates basal metabolic rate with the Mifflin–St Jeor equation:

Source: Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition, 1990;51(2):241–247.

Source: Accuracy within ~10% of measured resting metabolic rate (a separate systematic review, not a finding of the 1990 Mifflin paper): Frankenfield DC, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review.” Journal of the American Dietetic Association, 2005;105(5):775–789.

Limitation: Mifflin–St Jeor is developed and validated on healthy adults; it is less accurate at the extremes of body composition and was not developed for children, pregnancy, or clinical illness. The “unspecified” constant is Fignal's own midpoint, not a published value.

Maintenance calories = BMR × an activity factor. The exact values below (1.2, 1.375, 1.55, 1.725, 1.9) are a commonly used practical convention for estimating TDEE — a de facto industry standard rather than a figure published by any single health authority. Fignal reports them exactly as implemented:

Source: Scientific context (not the source of the five values above): Institute of Medicine (now NASEM), Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, 2005 — physical activity level (PAL) categories of sedentary 1.0–1.39, low active 1.4–1.59, active 1.6–1.89, very active 1.9–2.5. FAO/WHO/UNU, Human Energy Requirements, 2004.

These frameworks establish the evidence-based principle that resting energy expenditure should be scaled by a physical activity level, and they give scientific context for the size of that adjustment. Their PAL classifications are broad ranges and are not identical to, nor a direct validation of, Fignal's exact five multipliers.

Limitation: self-reported activity is the largest source of error in any TDEE estimate. Two people with the same profile can differ by several hundred calories a day.

Source: CDC, Healthy Weight, Nutrition, and Physical Activity — Losing Weight: a gradual, steady loss of about 1–2 pounds (0.45–0.9 kg) per week is what people are most likely to maintain, commonly achieved by reducing intake by roughly 500 calories per day. Fignal's ~0.5 kg/week projection pace sits inside that range (0.25 kg/week for muscle gain).

Limitation: the “500 kcal ≈ 0.45 kg/week” rule is a linear approximation. Real weight change slows as body mass falls, and short-term scale movement is dominated by water and glycogen. The 1,200 kcal floor is a safety stop, not a recommendation — very-low-calorie diets should only be followed under clinical supervision. Fignal never sets a target below 1,200 kcal/day and will flag an implausibly low maintenance estimate rather than act on it.

Protein targets are set per kilogram of body weight. Fignal's current multipliers, reported exactly as implemented:

Source: RDA floor 0.8 g/kg/day: Institute of Medicine DRI, 2005. Active adults 1.2–2.0 g/kg/day: Thomas DT, Erdman KA, Burke LM. “Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance.” Journal of the Academy of Nutrition and Dietetics, 2016;116(3):501–528. Resistance training benefit plateauing near ~1.6 g/kg/day: Morton RW et al., British Journal of Sports Medicine, 2018;52(6):376–384. Higher protein during energy restriction to preserve lean mass: Jäger R et al., “ISSN Position Stand: Protein and Exercise,” Journal of the International Society of Sports Nutrition, 2017;14:20.

Limitation: every multiplier above is within published ranges for healthy adults, but the exact value Fignal picks for your combination of goal and activity is an app-level choice, not a figure copied from a single guideline. People with kidney disease, liver disease, or who are pregnant should have protein intake set by a clinician.

A timeline is only projected when your current weight differs from the goal weight you entered. The pace assumed is ~0.25 kg per week for a muscle-gain goal and ~0.5 kg per week for every other goal, applied to the gap in either direction, based on the CDC gradual-change guidance above. Choosing “maintain weight” or “general health” does not by itself create a weight-loss plan or change your calorie target — if your current and goal weights match, the projection is simply “at your goal.” These are arithmetic projections, not predictions, and they ignore plateaus, water weight, menstrual cycle changes, and adherence.

Food identification, portion estimation, calories, and macros come from an AI model (Google Gemini, accessed through the Lovable AI Gateway) reading your photo or description. The red/yellow/green signal is Fignal's own heuristic summary of those estimated values against your stated goal, weighting factors such as added sugar, saturated fat, sodium, fiber, protein density, and degree of processing.

Limitation: these are estimates, not measurements. AI cannot see hidden oils, ingredients, portion depth, or recipe specifics, so calories and macros can be materially wrong. The signal is a general-education heuristic — it is not a clinical assessment, not a food-safety judgement, and it cannot account for allergies, intolerances, medication interactions, or any medical condition. Always read the actual product label where one exists.

In-app tips summarise mainstream public-health guidance from bodies such as the CDC, the World Health Organization, the U.S. Dietary Guidelines for Americans, and the NHS. They are general information for a healthy adult population, are not tailored to you, and should not be used to self-treat.

If you believe a formula, citation, or claim in Fignal is inaccurate, email fignalemail@gmail.com and we will review and correct it.