Data Source & Methodology
AuthoritativeDataSource: United States Department of Agriculture (USDA) MyPlate Food Group Plans (2000‑kcal baseline) and Dietary Guidelines for Americans 2020–2025; Mifflin, M.D. et al. (1990) Mifflin–St Jeor resting metabolic rate equation.
- USDA MyPlate Plan: myplate.gov/myplate-plan
- Dietary Guidelines 2020–2025: dietaryguidelines.gov
- Mifflin–St Jeor (1990): PubMed 2305711
All calculations strictly follow the formulas and data provided by these sources.
The Formula Explained
Basal Metabolic Rate (BMR):
\[ \text{BMR}_{male} = 10\,w + 6.25\,h - 5\,a + 5 \]
\[ \text{BMR}_{female} = 10\,w + 6.25\,h - 5\,a - 161 \]
where \(w\) = weight (kg), \(h\) = height (cm), \(a\) = age (years).
Total Daily Energy Expenditure (TDEE):
\[ \text{TDEE} = \text{BMR} \times \text{PAL} \]
Goal‑adjusted target calories:
\[ C_\text{target} = \text{TDEE} \times (1 + g) \quad \text{with } g \in \{-0.10, 0, +0.10\} \]
Daily servings per group are scaled from a 2000‑kcal baseline plan:
\[ S_i = S_{i,2000} \times \frac{C_\text{target}}{2000} \]
Glossary of Variables
- BMR: Basal Metabolic Rate (kcal/day) predicted by Mifflin–St Jeor.
- PAL: Physical Activity Level multiplier (1.2–1.9).
- Target calories: Calories/day after applying goal adjustment.
- Servings: Daily amount by food group (oz‑eq or cups; oils in grams).
How It Works: A Step‑by‑Step Example
Example: Female, 30 y, 175 cm, 70 kg, Moderate PAL 1.55, Maintain, 3 meals/day.
- Compute BMR: \(10·70 + 6.25·175 - 5·30 - 161 = 1496.\)
- TDEE: \(1496 × 1.55 ≈ 2319\) kcal.
- Target calories: Maintain → \(C_\text{target} = 2319\) kcal.
- Scale servings from 2000‑kcal baseline using \(C_\text{target}/2000 = 1.16\).
- Divide daily servings by meals to get per‑meal suggestions.
Frequently Asked Questions
Is this medical advice?
No. This tool provides educational estimates based on public guidelines. Consult a qualified clinician or registered dietitian for personal medical advice.
Why scale linearly from a 2000‑kcal plan?
USDA group targets are defined across calorie levels. Linear scaling provides a transparent approximation between levels. Rounded outputs are for practicality.
Can I customize macro ratios?
This calculator focuses on food‑group servings. Macro ratio planning can be layered on top but is outside this tool’s scope.
What counts as an oz‑equivalent?
For grains and protein foods, USDA uses “oz‑equivalents.” Examples are shown in the table (e.g., 1 slice bread ≈ 1 oz‑eq grains).
How accurate are PAL multipliers?
PAL ranges are population averages. Individual energy needs vary with body composition, non‑exercise activity, and health status.
Can I use this for children or older adults?
Outputs are tuned for ages 14–99. For children, adolescents, or frail older adults, consult age‑specific guidance.
Tool developed by Ugo Candido. Content reviewed by the CalcDomain Editorial Board.
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