Data Sources and Methodology
Primary references:
- Institute of Medicine (US) and National Academies. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005). AMDR for carbohydrates: 45–65% of total energy. View source.
- 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 (2016). Carbohydrate recommendations by training load (≈3–10 g/kg). View source.
All calculations are strictly based on the formulas and data provided by these sources.
The Formulas Explained
1) Carbs by calories
$$ \text{Carb grams} = \frac{\text{Calories} \times (\text{Carb%}/100)}{4} $$
4 kcal per gram of carbohydrate.
2) Carbs by body weight
$$ \text{Carb grams} = (\text{g/kg per activity}) \times \text{Body mass (kg)} $$
with activity-driven bands: sedentary 2–3, light 3–4, moderate 4–5, high 5–7, very high 7–10 g/kg (goal may shift the band by ±0.5 g/kg).
3) From TDEE (Mifflin–St Jeor)
$$ \text{BMR}_{\text{male}} = 10W + 6.25H - 5A + 5 \\ \text{BMR}_{\text{female}} = 10W + 6.25H - 5A - 161 $$
where W is weight (kg), H is height (cm), A is age (years).
$$ \text{TDEE} = \text{BMR} \times \text{Activity Factor} $$
$$ \text{Target Calories} = \text{TDEE} \times (1 + \Delta) $$
Then apply formula (1) to derive carb grams.
Glossary of Variables
| Variable | Meaning |
|---|---|
| Body weight | Your current body mass (kg or lb). |
| Training volume | Weekly training load guiding g/kg carbohydrate bands. |
| Goal | Weight change intent; shifts g/kg band or calories. |
| Daily calories | Total energy target for the day (kcal). |
| Diet style / Carb % | Preset or custom share of calories from carbohydrates. |
| Sex, Age, Height | Inputs for BMR in Mifflin–St Jeor when using TDEE. |
| Activity factor | Multiplier (1.2–1.9) converting BMR to TDEE. |
| Carb grams/day | Estimated daily grams of carbohydrates. |
| Carb calories | Energy from carbohydrates (grams × 4 kcal). |
| Per meal | Carb grams divided by number of meals. |
How It Works: A Step-by-Step Example
Scenario: 30-year-old female, 65 kg, 170 cm, moderate activity (1.55), weight loss standard (-15%), Balanced diet (50% carbs).
- Compute BMR (female): BMR = 10×65 + 6.25×170 − 5×30 − 161 = 650 + 1062.5 − 150 − 161 = 1401.5 kcal.
- TDEE = 1401.5 × 1.55 ≈ 2172 kcal.
- Target calories = 2172 × (1 − 0.15) ≈ 1846 kcal.
- Carb calories = 1846 × 0.50 ≈ 923 kcal; Carb grams = 923 ÷ 4 ≈ 231 g/day.
Result: ~231 g/day of carbohydrates, or ~77 g per meal if eating 3 meals.
Frequently Asked Questions (FAQ)
What percentage of calories should come from carbs?
The AMDR recommends 45–65% of calories from carbs for most adults. Choose the lower end for lower activity or specific goals, higher end for endurance or high-volume training.
How do training demands change carb needs?
As weekly training time and intensity rise, g/kg needs increase: roughly 2–3 (sedentary) up to 7–10 g/kg (very high endurance). Our weight-based method reflects this range.
Can I combine weight-based and calorie-based planning?
Yes. Many athletes validate both: a g/kg target and a percent-of-calories macro plan to ensure consistency.
Do I need to precisely match per-meal carbs?
No. Per-meal is a helpful average. Timing around training and fiber tolerance may shift distribution.
What about low-carb or ketogenic diets?
Low-carb often ranges 10–30% of calories. Keto typically keeps carbs ≈5% or below ~20–50 g/day. Consult your clinician for medical indications.
Is fiber counted in these carb grams?
Yes, the estimate is for total carbohydrate. Fiber is beneficial; track separately if you have specific GI or metabolic goals.
Are these results personalized medical advice?
No. This tool is educational and based on authoritative references. For medical conditions, seek guidance from a registered dietitian or physician.
Strumento sviluppato da Ugo Candido. Contenuti verificati da Registered Dietitian (RD).
Ultima revisione per l'accuratezza in data: .