Macros
How to Calculate Your Macros for Weight Loss: A Complete Guide for 2026
Knowing how to calculate your macros for weight loss is one of the most powerful steps anyone can take on
April 5, 2026
BMR · TDEE · BMI · macros · goal adjustment
A calorie calculator estimates your Total Daily Energy Expenditure (TDEE) — the number of calories your body needs each day to maintain its current weight, given your age, sex, height, weight, and activity level. TDEE combines two measurements: your Basal Metabolic Rate (BMR), which is the energy your body uses purely to sustain vital functions at rest, and an activity multiplier that accounts for movement. The methodology is endorsed by the Academy of Nutrition and Dietetics, the CDC's Healthy Weight programme, and the National Heart, Lung, and Blood Institute as the standard starting point for evidence-based dietary planning.
WellCal uses the Mifflin-St Jeor equation, the formula the Academy of Nutrition and Dietetics identifies as the most accurate for healthy adults. The equations are:
Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Your BMR is then multiplied by an activity factor (1.2 for sedentary through 1.9 for extremely active) to produce your TDEE. A 2005 validation study referenced by the
National Institutes of Health
found Mifflin-St Jeor predicted resting metabolic rate within 10% for 82% of tested adults — outperforming the older Harris-Benedict equation for non-obese populations.
Your daily calorie target is the foundation of any nutrition plan, but it works best alongside a full picture of your health. Once you know your TDEE, use WellCal's Macro Calculator to split those calories into protein, fat, and carbohydrate targets, and the Protein Calculator to confirm you're eating enough protein to support muscle maintenance. If you're also tracking metabolic health, check your score with the Diabetes Risk Calculator.
Your TDEE is not a fixed number. Eight evidence-based factors determine how many calories your body actually burns each day — understanding them helps you use your calorie target far more effectively.
BMR accounts for 60–70% of your total daily calorie expenditure, making it the single largest component of your TDEE. It covers the energy cost of heartbeat, respiration, thermoregulation, and cellular maintenance. According to the National Heart, Lung, and Blood Institute, a sedentary adult cannot easily change their BMR rapidly, but building lean muscle mass through resistance training elevates it over months. Use WellCal's Body Age Calculator to understand how your metabolic fitness compares to population norms for your age.
Exercise and non-exercise activity thermogenesis (NEAT — fidgeting, walking, standing) together account for 15–30% of daily energy expenditure in most adults. The activity multiplier applied to your BMR ranges from 1.2 (desk job, no exercise) to 1.9 (twice-daily training), meaning a highly active person burns up to 58% more calories than their sedentary counterpart at the same body weight. Research from the CDC recommends at least 150 minutes of moderate aerobic activity per week for healthy adults. Complement your calorie plan with WellCal's Sleep Calculator, since poor sleep is independently linked to reduced NEAT and increased hunger hormones.
Skeletal muscle burns approximately 13 kcal per kilogram per day at rest, while fat tissue burns only around 4.5 kcal/kg/day, according to research cited in the NIH's nutrition reference library. This means a person with more lean mass requires significantly more calories to maintain their weight — which is one reason men generally have higher TDEEs than women of equal body weight. Progressive resistance training, combined with adequate protein intake, is the most evidence-based strategy for increasing lean mass. Check your protein adequacy with WellCal's Protein Calculator alongside your calorie target.
BMR declines by roughly 2–3% per decade after age 20, partly due to age-related muscle loss (sarcopenia) and hormonal shifts. The 2020–2025 Dietary Guidelines for Americans reflect this: estimated calorie needs for sedentary women drop from 2,000 kcal at age 19–30 to 1,600 kcal at age 51+. Practically, this means recalculating your TDEE every 5 years or after any significant body composition change is important for preventing gradual, unnoticed weight gain. WellCal's BMI Calculator can help you monitor body composition changes over time alongside your calorie recalculations.
The thermic effect of food (TEF) — the calories your body burns digesting and absorbing nutrients — varies significantly by macronutrient: protein costs 20–30% of its own calories to digest, carbohydrates cost 5–10%, and fat just 0–3%. This means two people eating the same number of calories can have meaningfully different net energy availability depending on their diet composition. A high-protein diet therefore burns more calories through digestion alone. Use WellCal's Macro Calculator to optimise your macronutrient split alongside your calorie target, and the Fiber Calculator to ensure fibre intake supports satiety and digestive health.
A 2003 study published in the Journal of Clinical Endocrinology & Metabolism found that drinking 500 ml of water increased metabolic rate by 30% for up to 40 minutes, with roughly 40% of the effect attributed to thermogenesis from warming the water to body temperature. Chronic mild dehydration, which is common, is associated with reduced physical performance and can be misinterpreted as hunger — leading to unnecessary calorie intake. The National Academies of Sciences recommend 3.7 litres/day for men and 2.7 litres/day for women from all sources. Check your personal target with WellCal's Water Intake Calculator.
Sleep deprivation disrupts the balance of ghrelin (hunger hormone) and leptin (satiety hormone): a landmark study from the University of Chicago published in PLOS Medicine found that just two nights of short sleep (4 hours) increased ghrelin by 28% and decreased leptin by 18%, leading subjects to report 24% greater hunger. In practical terms, poor sleep effectively makes your calorie target harder to stick to, even if the number is correctly calculated. Adults sleeping fewer than 7 hours per night also tend to accumulate more visceral fat over time. Use WellCal's Sleep Calculator to calculate your optimal sleep window alongside your calorie plan.
Conditions including hypothyroidism, insulin resistance, polycystic ovary syndrome (PCOS), and Cushing's syndrome can reduce actual energy expenditure well below what any equation predicts. Conversely, hyperthyroidism elevates metabolic rate significantly. According to the Mayo Clinic, untreated hypothyroidism can slow metabolism enough to cause weight gain of several kilograms despite unchanged diet and activity. If you consistently gain weight while eating at or below your calculated TDEE, a thyroid panel or blood glucose assessment is warranted. WellCal's Diabetes Risk Calculator and Cholesterol Ratio Calculator can help you track related metabolic markers.
Your TDEE is not a fixed number. Eight evidence-based factors determine how many calories your body actually burns each day — understanding them helps you use your calorie target far more effectively.
BMR accounts for 60–70% of your total daily calorie expenditure, making it the single largest component of your TDEE. It covers the energy cost of heartbeat, respiration, thermoregulation, and cellular maintenance. According to the National Heart, Lung, and Blood Institute, a sedentary adult cannot easily change their BMR rapidly, but building lean muscle mass through resistance training elevates it over months. Use WellCal's Body Age Calculator to understand how your metabolic fitness compares to population norms for your age.
Exercise and non-exercise activity thermogenesis (NEAT — fidgeting, walking, standing) together account for 15–30% of daily energy expenditure in most adults. The activity multiplier applied to your BMR ranges from 1.2 (desk job, no exercise) to 1.9 (twice-daily training), meaning a highly active person burns up to 58% more calories than their sedentary counterpart at the same body weight. Research from the CDC recommends at least 150 minutes of moderate aerobic activity per week for healthy adults. Complement your calorie plan with WellCal's Sleep Calculator, since poor sleep is independently linked to reduced NEAT and increased hunger hormones.
Skeletal muscle burns approximately 13 kcal per kilogram per day at rest, while fat tissue burns only around 4.5 kcal/kg/day, according to research cited in the NIH's nutrition reference library. This means a person with more lean mass requires significantly more calories to maintain their weight — which is one reason men generally have higher TDEEs than women of equal body weight. Progressive resistance training, combined with adequate protein intake, is the most evidence-based strategy for increasing lean mass. Check your protein adequacy with WellCal's Protein Calculator alongside your calorie target.
BMR declines by roughly 2–3% per decade after age 20, partly due to age-related muscle loss (sarcopenia) and hormonal shifts. The 2020–2025 Dietary Guidelines for Americans reflect this: estimated calorie needs for sedentary women drop from 2,000 kcal at age 19–30 to 1,600 kcal at age 51+. Practically, this means recalculating your TDEE every 5 years or after any significant body composition change is important for preventing gradual, unnoticed weight gain. WellCal's BMI Calculator can help you monitor body composition changes over time alongside your calorie recalculations.
The thermic effect of food (TEF) — the calories your body burns digesting and absorbing nutrients — varies significantly by macronutrient: protein costs 20–30% of its own calories to digest, carbohydrates cost 5–10%, and fat just 0–3%. This means two people eating the same number of calories can have meaningfully different net energy availability depending on their diet composition. A high-protein diet therefore burns more calories through digestion alone. Use WellCal's Macro Calculator to optimise your macronutrient split alongside your calorie target, and the Fiber Calculator to ensure fibre intake supports satiety and digestive health.
A 2003 study published in the Journal of Clinical Endocrinology & Metabolism found that drinking 500 ml of water increased metabolic rate by 30% for up to 40 minutes, with roughly 40% of the effect attributed to thermogenesis from warming the water to body temperature. Chronic mild dehydration, which is common, is associated with reduced physical performance and can be misinterpreted as hunger — leading to unnecessary calorie intake. The National Academies of Sciences recommend 3.7 litres/day for men and 2.7 litres/day for women from all sources. Check your personal target with WellCal's Water Intake Calculator.
Sleep deprivation disrupts the balance of ghrelin (hunger hormone) and leptin (satiety hormone): a landmark study from the University of Chicago published in PLOS Medicine found that just two nights of short sleep (4 hours) increased ghrelin by 28% and decreased leptin by 18%, leading subjects to report 24% greater hunger. In practical terms, poor sleep effectively makes your calorie target harder to stick to, even if the number is correctly calculated. Adults sleeping fewer than 7 hours per night also tend to accumulate more visceral fat over time. Use WellCal's Sleep Calculator to calculate your optimal sleep window alongside your calorie plan.
Conditions including hypothyroidism, insulin resistance, polycystic ovary syndrome (PCOS), and Cushing's syndrome can reduce actual energy expenditure well below what any equation predicts. Conversely, hyperthyroidism elevates metabolic rate significantly. According to the Mayo Clinic, untreated hypothyroidism can slow metabolism enough to cause weight gain of several kilograms despite unchanged diet and activity. If you consistently gain weight while eating at or below your calculated TDEE, a thyroid panel or blood glucose assessment is warranted. WellCal's Diabetes Risk Calculator and Cholesterol Ratio Calculator can help you track related metabolic markers.
Your TDEE estimate is a powerful starting point, but no formula can see the full picture. Understanding these six limitations helps you interpret your result accurately and adjust intelligently over time.
Your daily calorie target is the foundation — these eight calculators help you build a complete, evidence-based picture of your health and nutrition from the ground up.
Knowing how to calculate your macros for weight loss is one of the most powerful steps anyone can take on
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