Protein and your cycle: nutrition needs explained

Q: How much protein do you need per day in the UK?

The UK guideline, called the Reference Nutrient Intake (RNI), is 0.75g of protein per kilogram of bodyweight a day. For an average 60kg woman that comes to around 45g of protein a day. It applies to healthy, lightly active adults. If you are very active, pregnant, or breastfeeding, your needs may be higher, so it is worth talking it through with a GP or registered dietitian.

Q: What is the best way to meet my protein needs?

Try to add a protein source to each of your meals and snacks. It will provide a steady supply of protein to your body and may also support feelings of fullness after your meals.

Q: What is the difference between the RNI and the RI shown on food packaging?

The RNI (Reference Nutrient Intake) of around 45g is a dietary guideline for the average (60kg) adult woman. The RI (Reference Intake) of 50g you see on food labels is a standard packaging figure used across the UK. They are not the same thing. The RI on a label helps you compare products, rather than setting a personal health target for you.

Pensive young lady sitting outside with a journal on her lap and a pen in her hand

Bloume content relating to health, wellbeing and nutrition has been reviewed and validated by relevant medical professionals in the UK, based on UK guidelines and practices applicable at the time of publication. Recommendations in other localities may differ from those found on our site and you should always seek the guidance or advice of relevant healthcare professionals in your area.

Protein plays an important role every day of your cycle. Understanding what it does and how to include it across the day can help you meet your needs and respond to changes in appetite.

What protein does in your body every day

Your body uses protein constantly. It provides amino acids used to build, repair and maintain body tissues. It is what you draw on to help make hormones, enzymes, and antibodies. So protein is not only something you need when you are exercising or getting over an illness. Your body uses it every day of your cycle.²

The UK Reference Nutrient Intake (RNI), which is the amount of a nutrient that is enough to ensure that the needs of nearly all a group (97.5%) are being met, is set at 0.75g of protein per kilogram of body weight a day. This is set at a level for a healthy, lightly active adult. For an average woman weighing 60kg, it would be a total of 45g of protein a day. The 50g you might see on food packaging is something different. That is the Reference Intake (RI), a standard labelling figure for an average adult. The RNI is a dietary guideline; the RI is used to show how much a food contributes to daily intake and to help compare products. It is not a personal protein requirement.¹

Protein, fullness, and staying satisfied

Protein tends to be more filling when compared with carbohydrates and fats. Including a source of protein, such as eggs, yoghurt, fish, meat, tofu, beans or lentils to your meals may help you stay fuller between meals. This is particularly useful in the week or so before your period when you can experience more cravings.³

Protein as part of a balanced meal

When you eat protein with carbohydrates, It may slow how quickly the meal leaves the stomach. This can help reduce the rise in blood sugar after eating. Steadier blood sugar can help some people avoid dips in energy through the day, which helps when cycle-related tiredness is already in the mix.⁴

Pairing carbohydrate foods with a protein source is a simple way to build a balanced meal that is filling and sustaining. Oats with Greek yoghurt (or protein soya yoghurt if you avoid dairy), wholegrain toast with eggs, or rice with tofu are everyday examples.

Yogurt bowl with blueberries on a table.

Why appetite may change before your period and how protein could help

If your appetite feels stronger in your luteal phase (ovulation until the first day of your period), there may be a physiological reason behind it. Your body may be using slightly more energy at rest at this time, although this varies and does not mean that everyone needs a set number of additional calories. Research suggests that appetite, cravings and food intake can also all increase during the luteal phase. Including protein at meals and snacks may help you feel more satisfied in your luteal phase.⁵

Spreading protein across the day

Rather than having most of your protein in one meal, try to include a source at each meal. Spreading protein across the day may help you feel more satisfied whilst supporting muscle maintenance and repair.⁷

Good sources include meat, fish, eggs, and dairy, along with legumes like lentils, chickpeas, and beans, plus tofu and tempeh. Mixing it up across the week gives you a broad range of amino acids and other nutrients too, such as iron and zinc. This is particularly important if you are only eating plant sources of protein. They contain all the essential amino acids, but in different proportions, so eating a varied diet across the day helps support overall intake.

Protein and everyday recovery across the cycle

Proteins provide amino acids that support cell repair, including the rebuilding of your uterine lining during and after your period. It also helps your immune system by making antibodies. Keeping your protein fairly steady through the cycle supports this ongoing work, whatever phase you are in.

If your appetite climbs in the luteal phase, reaching for protein-rich foods instead of higher-sugar snacks may feel more filling and sustain you for longer. It is a pattern worth watching in your own cycle.

If you have a health condition, or you are pregnant or breastfeeding, it is worth speaking with your GP or a registered dietitian before making big changes to your diet.

Frequently Asked Questions

How much protein do you need per day in the UK?

What is the best way to meet my protein needs?

What is the difference between the RNI and the RI shown on food packaging?

Sources

[1] Reference Intakes (RI) on UK Food Labels

The Reference Intake (RI) used as a standardised labelling convention for an average adult is 50g.
[2] Protein – British Nutrition Foundation

Protein is essential for the constant building, repair, and maintenance of all body cells, and for creating vital molecules like hormones, enzymes, and antibodies.
[3] The Role of Protein in Satiety: How It Helps Control Hunger and Cravings

Among the macronutrients, protein tends to be the most effective at promoting fullness, helping you feel satisfied for longer compared with carbohydrates or fats alone.
[4] The role of proteins and fats in blood sugar regulation

When you eat protein alongside carbohydrates, it slows digestion and the rate at which carbohydrates are absorbed, helping avoid sharp rises and dips in blood sugar.
[5] The Impact of Menstrual Cycle Phase on Athletes’ Performance: A Narrative Review

Some research suggests that protein needs may increase during the luteal phase due to a rise in progesterone, which may increase the rate at which the body breaks down protein.
[6] The Impact of Menstrual Cycle Phase on Athletes’ Performance: A Narrative Review

Total energy expenditure can increase slightly in the luteal phase, which may contribute to increased appetite and food cravings.
[7] Protein fact sheet

The body does not store protein as a reserve in the way it stores fat, so regular intake across the day is more useful than concentrating it in one meal.