Nutrition and Dietetics Calculators

Total Daily Energy Expenditure (TDEE) is the total calories burned per day, combining basal metabolic rate (BMR) with activity level. BMR is calculated using the Mifflin-St Jeor equation (most accurate for most adults): for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. TDEE = BMR × activity multiplier (1.2 sedentary to 1.9 very active). TDEE is the starting point for weight management — caloric deficit for loss, surplus for gain.

The RDA for protein is 0.8 g/kg/day for sedentary adults — a minimum, not an optimal target. For muscle preservation and growth: 1.6–2.2 g/kg/day for resistance-trained individuals (per ISSN position stand). For older adults (>65 years): 1.2–1.6 g/kg/day to prevent sarcopenia. For critically ill patients: 1.2–2.0 g/kg ideal body weight per day. In obesity, protein targets are calculated on adjusted body weight, not actual weight, to avoid over-prescription.

The Malnutrition Universal Screening Tool (MUST) scores three components: BMI (<18.5 = 2 points, 18.5–20 = 1 point), unintentional weight loss (>10% = 2 points, 5–10% = 1 point), and acute disease effect (no nutritional intake >5 days = 2 points). Score 0 = low risk (routine care); 1 = medium risk (observe, monitor); ≥2 = high risk (refer to dietitian, initiate nutrition support). MUST is validated for hospital and community settings and recommended by BAPEN.

General macronutrient ranges (AMDR): carbohydrates 45–65% of calories, protein 10–35%, fat 20–35%. For weight loss: higher protein (30–35%) preserves lean mass during caloric deficit. For endurance athletes: higher carbohydrates (55–65%) to fuel glycogen stores. For ketogenic diets: fat >70%, carbohydrates <5–10% (typically <50 g/day). These are starting targets — individual response, food preferences, and medical conditions should drive individualization.

IOM pregnancy weight gain guidelines by pre-pregnancy BMI: underweight (BMI <18.5) = 28–40 lbs (12.5–18 kg); normal weight (18.5–24.9) = 25–35 lbs (11.5–16 kg); overweight (25–29.9) = 15–25 lbs (7–11.5 kg); obese (≥30) = 11–20 lbs (5–9 kg). Rate of gain matters too: ~1–4 lbs in the first trimester, then ~1 lb/week in the second and third. For twins: add approximately 10 lbs to singleton targets.

The glycemic index (GI) ranks foods by how quickly they raise blood glucose relative to pure glucose (GI = 100). Low GI (<55): oats, legumes, most fruits; medium GI (55–69): whole wheat bread, basmati rice; high GI (≥70): white bread, white rice, potatoes. Glycemic load (GL = GI × carbohydrate grams ÷ 100) accounts for portion size and is more clinically meaningful. Low-GI diets are associated with improved glycemic control in type 2 diabetes and modest weight loss benefits, per Cochrane review evidence.