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Teenage girls (14-18): calorie and protein needs
Adolescent girls carry the highest iron reference intake of any group on this site while also being the group where energy intake most often gets deliberately restricted. Those two facts sit badly together, and this page treats that as the main point.
These are population averages, not a plan for you. Energy and protein needs in teenage girls (14-18) are individualised by a midwife, doctor or registered dietitian who knows your history, your measurements and your blood work. Do not use this page to decide to eat more or less than you have been told to.
GrowthWomenReference age 16
The energy arithmetic is the same as for boys — Mifflin-St Jeor under a physical activity level, with the important caveat that the equation was built for adults and reference bodies use age-specific equations plus a growth allowance for under-18s. The table is a rough floor, not a target, and it is deliberately printed with a range of activity levels so that the size of the activity effect is obvious.
What differs is the nutrient risk profile. Menstrual iron losses begin in this age band, and the reference intake for menstruating women is roughly half again the male value. At the same time this is the group in which restrictive eating patterns most commonly start. Low energy intake and high iron need is a bad combination, and it does not show up on a scale — it shows up as tiredness, poor recovery from training, and eventually as blood work.
There is a specific pattern worth naming: an adolescent girl who trains seriously and eats to a number rather than to hunger can end up in a state of low energy availability, where intake covers neither training nor growth. The consequences include disrupted or absent periods and reduced bone mineral accrual at exactly the age when bone is being built. Missing or irregular periods in an athlete are not a convenient side effect; they are a reason to see a doctor.
The adjustment for this stage
No fixed increment — growth is handled through activity level and the growth spurt, not a flat addition.
PAL 1.7 is a moderately active adolescent. As with boys, the real spread between a training week and a holiday week is far larger than the spread between body sizes.
Source: Human energy requirements — Joint FAO/WHO/UNU Expert Consultation (physical activity level framework) · checked 2026-09-02
The equation this page uses
BMR (men) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
BMR (women) = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Daily target = BMR × 1.70Worked through for the middle row of the table below: a woman of 65 kg and 168 cm at age 16 has a Mifflin-St Jeor BMR of about 1 459 kcal. Multiplied by PAL 1.70 that is 2 480 kcal, which is the daily estimate.
Worked example: by height and weight
| Body weight | 155 cm | 162 cm | 168 cm | 175 cm |
|---|---|---|---|---|
| 45 kg | 2 002 | 2 077 | 2 140 | 2 215 |
| 55 kg | 2 172 | 2 247 | 2 310 | 2 385 |
| 65 kg | 2 342 | 2 417 | 2 480 | 2 555 |
| 75 kg | 2 512 | 2 587 | 2 650 | 2 725 |
| 85 kg | 2 682 | 2 757 | 2 820 | 2 895 |
Worked example: how age moves it
| Age | 45 kg | 55 kg | 65 kg | 75 kg | 85 kg |
|---|---|---|---|---|---|
| 14 | 2 157 | 2 327 | 2 497 | 2 667 | 2 837 |
| 15 | 2 149 | 2 319 | 2 489 | 2 659 | 2 829 |
| 16 | 2 140 | 2 310 | 2 480 | 2 650 | 2 820 |
| 17 | 2 132 | 2 302 | 2 472 | 2 642 | 2 812 |
| 18 | 2 123 | 2 293 | 2 463 | 2 633 | 2 803 |
What changes if your activity is different
| Activity level | What it describes | kcal a day |
|---|---|---|
| PAL 1.4 | Sedentary or low activity — desk work, little planned exercise | 2 043 |
| PAL 1.6 | Moderately active — some walking, light training two or three times a week | 2 334 |
| PAL 1.8 | Active — on your feet at work, or training most days | 2 626 |
| PAL 2.0 | Very active — physical job plus training, or high training volume | 2 918 |
Protein for this stage
EFSA's population reference intake for adolescents is around 0.9 g of protein per kg of body weight a day. Girls in this age band are the group where intake most often drifts below it during periods of restriction.
| Body weight | Protein, lower g/day | Protein, upper g/day | kcal from the lower figure | Share of the daily estimate |
|---|---|---|---|---|
| 45 kg | 41 | 45 | 162 | 8% |
| 55 kg | 50 | 55 | 198 | 9% |
| 65 kg | 59 | 65 | 234 | 9% |
| 75 kg | 68 | 75 | 270 | 10% |
| 85 kg | 77 | 85 | 306 | 11% |
Source: Human energy requirements — Joint FAO/WHO/UNU Expert Consultation (physical activity level framework) · checked 2026-09-02
Your own numbers
Calculate it for your own body
JavaScript is off, so use the worked-example tables on this page — they are computed on the server from the same equation.
Protein band on this page: EFSA's population reference intake for adolescents is around 0.9 g of protein per kg of body weight a day. Girls in this age band are the group where intake most often drifts below it during periods of restriction.
The nutrients that matter most here
- Iron. Menstrual losses begin during this stage. EFSA sets the reference intake for menstruating women at 16 mg a day against 11 mg for men and postmenopausal women — the largest single-nutrient gap between the sexes in the whole reference table.
- Calcium. Peak bone mass is built now. Restriction during adolescence has consequences that show up decades later, which is the strongest argument on this page against under-eating.
- Vitamin D. Pairs with calcium; northern winters supply none from sunlight.
- Folate. Reference intakes rise sharply if pregnancy becomes possible, which is why folate advice is framed around all women of childbearing age rather than only those who are pregnant.
- Iodine. Thyroid function and growth; dairy, white fish and iodised salt are the usual carriers in Northern Europe.
Source: EFSA Dietary Reference Values — energy, protein and micronutrients (European Food Safety Authority) · checked 2026-09-02
Nutrient reference values are population figures. This page never tells you to take a supplement or how much of one to take — that is a decision for a clinician who can see your blood work and your medicines.
What to actually do
- Eat to hunger and to the training week rather than to a daily number.
- Keep iron-rich foods paired with a vitamin C source in the same meal, which improves absorption of the plant forms.
- Do not skip fuelling around sport. Under-fuelled training is the mechanism behind most of the harm in this group.
- Missing periods, persistent fatigue or stress fractures are all reasons to see a doctor rather than to adjust a spreadsheet.
Frequently asked questions
Why is the iron figure so much higher for girls?
Menstrual losses. EFSA sets 16 mg a day for menstruating women against 11 mg for men and postmenopausal women.
Is it normal for periods to stop when training hard?
It is common, and it is not normal in the sense of being harmless. It is a reason to see a doctor, because it is often a signal that energy intake is not covering training and growth.
Which equation is this based on?
Mifflin-St Jeor for the resting figure, multiplied by a physical activity level of 1.70, with no flat increment for this stage.
Can I use this instead of seeing a professional?
No. These are population reference values. A midwife, doctor or registered dietitian is the only person who can turn them into a plan for you.
Other life stages
Pregnancy, first trimester
about +70 kcal a day on top of the pre-pregnancy requirement
Pregnancy, second trimester
about +260 kcal a day on top of the pre-pregnancy requirement
Pregnancy, third trimester
about +500 kcal a day on top of the pre-pregnancy requirement
Breastfeeding
about +500 kcal a day while breastfeeding exclusively
Teenage boys (14-18)
no fixed increment — growth is handled through activity level and the growth spurt, not a flat addition
Adults over 65
no addition — the requirement falls with lean mass and activity, while the protein target rises
All life stages · TDEE calculator · Macro split · Exercise library · Nutrient toplists
A reference value is a starting point, not an answer
Log two weeks in TempoLife and you have your own figure — what you ate, what you moved, and what your weight actually did.