- Under-eating is common in women who train and shows up as missed periods, injuries and fatigue.
- Protein targets are the same per kg as for men: roughly 1.6 to 2.2 g per kg a day.
- Women aged 19 to 50 need nearly twice as much iron as men, especially with heavy periods.
- Evidence for eating differently in each phase of your cycle is weak. Respond to your own symptoms.
- Missing or irregular periods are not a normal side effect of training. See your GP.
Eating enough comes first
The most important nutrition issue for many women who train is simply eating enough. Diet culture, busy lives and the idea that training should always come with a calorie deficit mean that plenty of women train hard on too little food.
When energy intake does not cover the cost of training plus the energy your body needs for everything else, you are in low energy availability. Over time this can lead to a condition called RED-S, relative energy deficiency in sport. It affects hormones, bones, immunity, mood and performance, and it can happen whether or not you look underweight.
Warning signs to take seriously:
- Periods that become irregular, lighter or stop, when you are not pregnant and not on hormonal contraception that affects bleeding
- Stress fractures or repeated injuries
- Frequent colds and infections
- Constant tiredness, low mood or poor sleep
- Performance that stalls or drops despite consistent training
- Feeling cold a lot, or noticeable hair loss
If these apply, see your GP. Missing periods are not a badge of training hard. They are a signal that something needs attention.
Protein, carbs and fat
Protein needs per kg are the same as for men: roughly 1.6 to 2.2 g per kg of body weight a day if you lift regularly. Many women eat well below this, especially at breakfast. A 65 kg woman would aim for about 105 to 145 g a day, spread over three or four meals. See how much protein you need.
Carbohydrate fuels hard training. Cutting it heavily is one of the fastest routes to flat sessions and low energy availability. Scale it to your training, with bigger portions around your hardest days.
Fat supports hormone production. Very low-fat diets, below around 20% of calories for long periods, can make it harder to meet energy needs and may contribute to hormonal disruption. Include olive oil, nuts, seeds, avocado and oily fish.
A practical check is to look at a typical training day. If breakfast is a coffee, lunch is a salad with little protein and dinner is the first proper meal, you are probably under-fuelled for an evening session. Adding a protein-rich breakfast and a carbohydrate snack in the afternoon often transforms how training feels within a couple of weeks.
Iron, calcium and vitamin D
Women aged 19 to 50 need 14.8 mg of iron a day, compared with 8.7 mg for men, because of blood lost through periods. Heavy periods, plant-based diets, endurance training and blood donation all increase the risk of running low. Tiredness, breathlessness, pale skin and noticeable heartbeats are common signs. Our guide to iron and training explains what to eat and when to get tested.
Bone health matters at every age, but especially if you have had periods of under-eating or missed periods. Get 700 mg of calcium a day from dairy or fortified alternatives, follow NHS advice on vitamin D, and keep lifting. Strength training is one of the best things you can do for your bones, as covered in strength training for women.
The menstrual cycle
Cycle syncing, or changing what you eat and how you train for each phase of your cycle, is popular online. The research so far is inconsistent. There is not good evidence that most women need different macronutrients in different phases.
What is well recognised is that symptoms vary a lot between women. Some notice more hunger, cravings or bloating in the days before a period. Others have heavy or painful periods that affect training. A practical approach is to track your cycle and symptoms for a few months and adjust based on what you notice:
- If appetite rises before your period, plan a slightly bigger snack or meal rather than fighting it
- If you feel flat, reduce intensity for a session or two rather than skipping training entirely
- If periods are very heavy, painful or disrupting your life, see your GP, as treatment can help
Pregnancy, postpartum and menopause
Trying for a baby and pregnancy: the NHS advises taking 400 micrograms of folic acid a day from before conception until 12 weeks of pregnancy, and 10 micrograms of vitamin D a day. Some foods should be avoided, and alcohol is best avoided completely. Your midwife or GP will advise on training and nutrition through pregnancy.
After birth: energy needs remain higher if you are breastfeeding, so this is not the time for an aggressive diet. Build back gradually with guidance, particularly around pelvic floor and abdominal recovery. On-site physiotherapy at Lycan Strength covers women's health, and members get 20% off treatment.
Perimenopause and menopause: falling oestrogen affects bone density, muscle, body fat distribution, sleep and mood. Prioritise protein, calcium and vitamin D, and keep lifting. HRT is a conversation to have with your GP. Our guide to menopause and fat loss covers the body composition side.
Supplements, body image and support
Creatine works for women in much the same way as for men, with better training quality and strength over time and a small, usually temporary rise in water weight. Vitamin D is advised for everyone in the UK in autumn and winter. Iron supplements should only be taken on a GP's advice after a blood test.
Training can do a lot for how you feel about your body, but gym culture can also feed unhelpful comparisons and rigid eating. If you notice intense guilt around food, rules you feel unable to break, eating in secret, or compensating for food with exercise, speak to your GP. The UK eating disorder charity Beat also offers confidential support.
If you are preparing for a race, the HYROX for women guide covers training considerations, and the same fuelling principles here apply.
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Questions
How much should a woman eat when training?
It depends on size, training volume and goals, but enough to fuel training, recover and maintain regular periods. Constant fatigue, missed periods or stalled progress suggest you may need more.
Should women eat differently from men for muscle building?
The principles are the same: enough protein per kg, enough energy and progressive training. Women need more iron before the menopause and should pay particular attention to bone health.
Is it normal to lose your period from training?
No. It is usually a sign of low energy availability or another health issue and should be checked by your GP.
Should I change my diet around my period?
Only if your symptoms call for it. Many women benefit from a little extra food when appetite rises before a period, and from seeing a GP if periods are very heavy or painful.
General guidance for healthy adults. If you have a medical condition, injury or are pregnant, check with a health professional before changing your training or diet.
