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Fuelling for a High Activity Week: How Nutrition Shifts with Your Cycle

by Samaira Farid,
Rose Constantine
Medically reviewed by Rose Constantine
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.

A high activity week can bring a particular kind of tiredness. The heaviness in your legs by day three, the hunger that arrives earlier than you expect, the way recovery feels slower than it should. Whilst there can be many factors at play, often it comes down to fuel. As your training volume climbs, what your body needs from food shifts in ways that go beyond simply eating more. Getting the timing, the components and the amount of what you eat right can be the difference between a week that builds fitness and one that leaves you running on empty.1

This is general information rather than medical or dietetic advice. If you have a specific health concern, or a condition that affects how you eat, your GP or a registered dietitian can give you guidance built around you.

Carbohydrate timing and fuelling for high output

When your legs start to feel empty partway through a session, it is possible that glycogen may be running low. Carbohydrate is one of your body's main fuels for activity, supplied through the blood as glucose and stored as glycogen in your muscles and liver. Stores are limited, and the speed that it is used up has many variables including exercise duration, intensity, starting glycogen, fitness, carbohydrate intake, exercise type to name but a few. Across a high activity week, topping them back up consistently can help you to hold your performance across session after session.234

Eating a carbohydrate-rich snack or meal two to three hours before you train tops up your glycogen stores, so you start each session with more in the tank. For hard sessions that run over an hour, aiming for around 30 to 60 grams of carbohydrate per hour can help keep blood glucose supply to your muscles steady. Easy options include bananas, low-fibre cereal bars, sports drinks or gels. These are general sports nutrition figures, and what your stomach tolerates mid-session varies from person to person.56

If you have completed a hard endurance session and have another demanding session coming up the following day, specialist sports guidance points to around 1.0 to 1.2 grams of carbohydrate per kilogram of body weight per hour. Spacing that across the first four hours helps your stores refill. A recovery meal or snack containing roughly three parts carbohydrate to one part protein is sometimes used as a practical guide, helping to provide carbohydrate for glycogen replenishment alongside protein for muscle repair. These are approximate targets rather than fixed rules. A registered dietitian can help you work out what fits your body and your training load.14

Protein for training recovery

Your protein needs climb when you are training hard. Most adults need around 0.75 grams of protein per kilogram of body weight a day. At endurance training levels, specialist sports guidance puts the range closer to 1.2 to 2.0 grams per kilogram a day. That range comes from specialist sports sources rather than general dietary guidelines. The right figure for you depends on your size, as well as the frequency, intensity and duration of your training.716

Timing matters as much as the amount. Taking 15 to 25 grams of protein with some carbohydrate within 30 minutes to two hours of finishing may ease muscle soreness and help your body repair. Some specialists suggest the first 60 minutes after a session is especially useful. Spreading protein across each meal through the day tends to support recovery better than loading it all into one sitting.17

Recovery foods that pair protein with carbohydrate include a smoothie made with Greek yoghurt and fruit, or a chocolate milkshake after a session. If you eat dairy-free, a soya yoghurt or fortified plant milk works the same way. These are practical choices for straight after training rather than everyday staples.18

Asian woman eating a bowl of food with a smile on her face.

Iron awareness at high training output

When your iron is low, you might notice your performance dropping off, a tiredness that lingers, or breathlessness during activity that feels out of step with your effort. Iron helps make haemoglobin, the protein in your red blood cells that carries oxygen to your muscles. If haemoglobin falls, your blood cannot carry as much oxygen to your working muscles. These symptoms can have many causes so, if you are noticing these signs, it is worth speaking to your GP rather than trying to diagnose or supplement on your own.819

Repeated, long term heavy training may increase your risk of low iron stores via several mechanisms including through sweat and turning over red blood cells faster, which can push your needs up particularly if you are training at a high level, frequently, over a long period time. In the UK, the recommended daily intake is 8.7mg for men, and 14.8mg for women aged 19 to 50. There is no separate UK target for athletes, but regularly including iron-rich foods is particularly important if you train heavily, menstruate or avoid major dietary sources of iron.9

Dietary iron comes in two forms. Haem iron, found in meat, and non-haem iron, found in plant foods like lentils, beans, fortified cereals and dark leafy greens. Your body takes up non-haem iron less easily, but pairing it with vitamin C, say a glass of orange juice or some peppers with your meal, helps you absorb more. Tea and coffee contain compounds that can reduce iron absorption, so if you are keeping track of your intake it helps to leave a gap around mealtimes.20

How your cycle phase shifts fuelling needs during high activity

Fuelling around your cycle is a newer area of sports science. Much of the research so far comes from small studies, with findings that are not always consistent, and there is not yet enough evidence to support established phase-specific nutrition guidelines. With that in mind, treat the information below as possible insights rather than firm recommendations. If you want to apply it to your own training, a registered sports dietitian can help you shape it around you.

The follicular phase and carbohydrate availability

During the follicular phase, the first half of your cycle (from when your period starts until you ovulate), some research has suggested your body may do well with more carbohydrate available, particularly during longer, more demanding exercise. With this in mind, slightly increasing the proportion of carbohydrate in your meals before and after exercise may support you during this phase. This is emerging guidance from small studies sources rather than a clinical recommendation.10

The luteal phase and a shift in fuel use

During the luteal phase, the second half of your cycle (from when you ovulate, up until when your period starts), your resting metabolic rate (the energy your body burns at rest) may rise. Some research indicates an increase of between 30-120 extra calories a day, although this varies and may be difficult to distinguish from normal day-to-day changes. Some small studies suggest that your body may lean more on fat for fuel and conserve more glycogen, depending on the type of exercise. The amount of carbohydrate you eat should still reflect the length and intensity of your session rather than being reduced automatically. However it might be worth tracking changes in hunger, symptoms and training response across several cycles to help identify whether you personally benefit from adjusting your food intake.1112

Menstruation, inflammation and recovery

During your period, your body moves through an inflammatory process, some research suggests that recovery from sessions can take a little longer than at other points in your cycle. Iron-rich foods are worth prioritising, since menstrual blood loss feeds into your overall iron turnover. The steps from the iron section above are especially relevant in this phase.13

Putting it together across the week

Across a high activity week, steady fuelling matters more than any single meal. Getting enough carbohydrates before and during (if longer than 60 minutes) and after sessions, keeping protein on your plate at every meal for recovery, and regularly consuming iron-rich food can help to provide your body what it needs to keep performing. The specific targets within this article are based on early, small studies, and needs will be different depending on many factors, including body weight, training intensity and how you respond as an individual.15

If fatigue, slow recovery, or symptoms like breathlessness keep showing up during your high activity weeks, raise them with your GP. For nutrition guidance built around your training, a registered dietitian or sports nutritionist is the right place to start.

Frequently Asked Questions

Sources

  • [1] Sport & Exercise Nutrition

    Getting the timing, the components and the amount of what you eat right can be the difference between a week that builds fitness and one that leaves you running on empty.

  • [2] Fundamentals of glycogen metabolism for coaches and athletes

    Carbohydrates are stored in limited quantities as glycogen in human skeletal muscle and the liver, serving as a primary substrate for muscle contraction during exercise

  • [3] Optimizing fat oxidation through exercise and diet

    Outlines that the rate of muscle glycogen utilization during activity depends on multiple factors, including exercise intensity, duration, baseline muscle glycogen stores, and physical training status

  • [4] Skeletal Muscle Glycogen Content at Rest and During Endurance Exercise in Humans: A Meta-Analysis

    Demonstrates that consistent carbohydrate intake to replenish muscle glycogen stores is essential for maintaining sustained performance and power output across consecutive high-intensity training sessions

  • [5] Sport & Exercise Nutrition

    For sessions lasting over an hour, aiming for around 30 to 60 grams of carbohydrate per hour can help maintain blood glucose and keep muscles working. Practical sources include bananas, low-fibre cereal bars, sports drinks or gels.

  • [6] International society of sports nutrition position stand: nutrient timing

    Confirms that consuming a carbohydrate meal 2–3 hours pre-exercise optimizes glycogen stores, and intake of 30–60 grams of easily digestible carbohydrates per hour (such as gels, sports drinks, or bananas) during sessions lasting over 60 minutes maintains blood glucose levels and sustains exercise performance

  • [7] Sport and exercise

    The right figure depends on your size , as well as the frequency, intensity and duration of your training

  • [8] Iron deficiency, supplementation, and sports performance in female athletes: A systematic review

    Explains that iron is an essential component of haemoglobin required for oxygen transport to active skeletal muscles, and low iron status directly impairs aerobic capacity, leading to premature fatigue, breathlessness, and

  • [9] Government Dietary Recommendations

    Athletes who train heavily can lose iron through sweat and have a higher turnover of red blood cells, which may increase their requirements. In the UK, the recommended daily intake is 8.7mg per day for men and 14.8mg per day for women aged 19 to 50.

  • [10] Fuelling the female athlete: Carbohydrate and protein recommendations

    Notes emerging research suggesting female athletes may benefit from higher relative carbohydrate availability during the follicular phase to support performance during demanding exercise, while highlighting that current evidence stems from small studies and requires further clinical validation

  • [11] Resting metabolic rate fluctuations across the menstrual cycle: a systematic review

    Highlights small-study evidence suggesting a subtle shift toward fat oxidation during certain exercise modalities in the luteal phase, while emphasizing that total carbohydrate intake should still be driven by overall exercise duration and intensity rather than cycle phase alone

  • [12] Glucose kinetics and exercise performance during phases of the menstrual cycle: effect of glucose ingestion

    Demonstrates that resting metabolic rate (RMR) increases significantly during the luteal phase compared to the follicular phase (approximately 30 to 120 kcal/day), though individual variation makes tracking personal symptoms and energy levels over multiple cycles recommended.

  • [13] Exercise-Induced Muscle Damage During the Menstrual Cycle: A Systematic Review and Meta-Analysis

    During menstruation, the body undergoes an inflammatory process and recovery from training sessions may take longer. Protein demands can increase to support cellular repair following blood loss, and prioritising iron-rich foods is also relevant.

  • [14] Nutrition and Athletic Performance

    Specialist sports nutrition guidance suggests consuming around 1.0 to 1.2 grams of carbohydrate per kilogram of body weight per hour for the first four hours after hard endurance training to support glycogen replenishment. A recovery meal at a ratio of roughly 3 parts carbohydrate to 1 part protein is a common approach.

  • [15] Sports Nutrition Fundamentals To Improve Performance

    Optimal nutrition helps maintain high-level training, enhances recovery, and ensures sufficient energy for all bodily functions.

  • [16] Sport & Exercise Nutrition

    For those training at endurance levels, the protein range is approximately 1.2 to 2.0 grams per kilogram of body weight per day. Most adults need around 0.75 grams per kilogram per day.

  • [17] Recovery nutrition by Anita Bean

    Consuming 15 to 25 grams of protein alongside some carbohydrate within 30 minutes to two hours after training can help reduce muscle soreness and support repair. Some sports nutrition specialists suggest the first 60 minutes after a session is particularly effective.

  • [18] Sport & Exercise Nutrition

    Spreading protein across every meal throughout the day supports consistent recovery. Recovery foods that combine protein and carbohydrate include a smoothie made with Greek yoghurt and fruit, or a low-fat chocolate milkshake.

  • [19] Essential minerals: iron

    Iron plays a central role in making haemoglobin, which carries oxygen to your muscles. When iron is low, oxygen delivery falls and you may notice reduced exercise performance, persistent fatigue, or shortness of breath during activity.

  • [20] Iron in your diet

    There are two forms of dietary iron: haem iron from meat and non-haem iron from plant foods. Pairing non-haem iron with a source of vitamin C can improve absorption. Tea and coffee reduce iron absorption and it helps to avoid them close to mealtimes.