If your period has disappeared since you’ve been eating very “clean” or following a ketogenic diet, this article is for you.

Is not having a period really a problem?

Yes, because ovulation isn’t just about making babies. It’s how women produce hormones, particularly progesterone – your calming, protective hormone. When you aren’t ovulating, progesterone and other key hormones are low, which can make you feel anxious, wired, or struggle to sleep.

Regular ovulation supports:

• • Balanced hormones – preventing PMS, heavy periods, breast tenderness, and fibroids

• • A calm, well-regulated nervous system

• • Healthy thyroid function

• • Strong bones

• • Anti-inflammatory and immune balance

• • Mental clarity and focus

Why this matters so much for teenagers

Adolescence is a time of enormous demand: growing, laying down bone density, and establishing hormonal rhythms all at once. Young women need more consistent nourishment than older women with established cycles, and even more than their male friends.

Missing periods in teenagers are sometimes dismissed as “normal” – but frequently, the body simply isn’t getting what it needs at this very demanding time. We know that bones built in the teens and twenties are what you’ll rely on in your 60s and 70s. Hormonal patterns established in adolescence set the template for reproductive life. So, a missing period at seventeen is not something to ignore.

Why your brain decides whether you get a period

If your period has disappeared, it is because your brain made this decision for a reason.

Your brain is in constant communication with your ovaries. At the centre of this system sits the hypothalamus – no larger than an almond, yet responsible for deciding whether your body feels safe enough to ovulate and have a period.

It is exquisitely sensitive to both energy availability and perceived stress. When your brain senses any form of threat – the hypothalamus downregulates the hormonal signals required for ovulation.

Your body is well adapted to short bursts of stress. We are designed to respond quickly to danger, then return to a calm, regulated state once it has passed. But when stressors are experienced consistently every day, your brain begins to interpret your environment differently.

This is the “tiger chase” effect. Even without a real tiger, your body reacts the same way to modern stressors: skipping meals, nutrient gaps, over-exercising, or chronic emotional pressure. Survival mode kicks in, and ovulation is paused.

From a biological perspective, reproduction is a luxury. If your body does not feel safe or sufficiently nourished, it will always prioritise survival first.

This can happen very easily.

Many young women don’t realise how subtly this can occur. Skipping breakfast, having a light lunch, eating “healthily” but not quite enough for your needs, or cutting carbohydrates because of health advice or dietary trends can all signal scarcity to your brain.

Intermittent fasting has also been popular in recent years, yet it does not always serve younger women in the same way it can work for older women and most men.

Stress in all its forms also matters. Emotional pressure, a busy lifestyle, exams – are all part of our modern times adding to this smartphones which keep us in constant ‘on mode’ with very little downtime – all send the same message to your brain. Beyond adequate nutrition, your body is looking for consistency and a sense of safety.

Why carbohydrates are essential for restoring your period

While protein and fat are essential for healthy periods, carbohydrates play a particularly important role in signalling energy availability to the brain.

When carbohydrate intake is too low, levels of key metabolic hormones like insulin and leptin drop. These hormones normally tell the hypothalamus that energy is available. When they fall, the brain interprets scarcity and suppresses ovulation.

This can happen even if overall calorie intake seems sufficient.

One large prospective study of over 18,000 women found diets including whole, fibre-rich carbohydrates (vegetables, fruit, legumes) were linked with improved fertility outcomes. Diets high in refined, high-glycaemic carbohydrates were associated with increased risk of ovulatory infertility.

So it’s not just about eating more carbs; it’s about the right kind of carbs. Whole-food carbohydrates signal to your brain and ovaries that conditions are safe for ovulation. Highly processed carbs tend to do the opposite.

In my practice, I recommend a minimum of 120 grams of whole-food carbohydrates per day to support ovulation. If you are very active, doing lots of sports, or recovering from long-term period issues, you’ll likely need more. 

Low carbohydrate diets can also cause other symptoms such as mid-afternoon slumps, anxiety, brain fog, low blood pressure, and dizziness.

A caveat – when low-carb or ketogenic diets support women’s health

Nutrition is nuanced. There are no blanket approaches that work for every woman.

I am not against ketogenic or low-carbohydrate diets – but they are context-dependent. Medicinal ketogenic diets have well-established roles for improving conditions such as epilepsy, Alzheimer’s, diabetes, and some cancers. Also, many women over 45 may benefit from lower carbohydrate intake to support insulin sensitivity, and improve metabolic flexibility.

For women with polycystic ovary syndrome (PCOS), particularly with insulin resistance or higher body weight, very low-carbohydrate or ketogenic diets can actually restore ovulation. But even here, I would encourage you explore this with a qualified practitioner, as low-carbohydrate diet even in PCOS is best used as a temporary reset tool.

Your ancestry also provides part of the blueprint for the diet that best supports your cycle. If your roots stem from populations that traditionally thrived on higher protein and fat intake, such as the Inuit, your body may tolerate lower carbohydrate intake better than someone whose ancestry comes from warmer regions.

However, this is not the same situation as hypothalamic amenorrhoea, which is far more common in younger women. In this context, the problem is insufficient energy availability, not excess insulin. Restricting carbohydrates further can reinforce the very signal that is suppressing ovulation.

The same dietary approach will not work for everyone and may even make things worse.

How to check if you’re eating enough

Other than assessing detailed diet diaries of my clients, I sometimes use Energy Availability (EA) to get a clearer picture, especially for younger women who do regular training. It looks at how much energy is left for your body after activity – not just exercise, but daily movement like walking or being on your feet.

If you want to try it at home, there are free online calculators which estimate your EA, even without exact body composition scales. If your number is below 30 kcal per kg of fat-free mass, that’s a red flag you may be under-eating for your needs – which is very common – this is what impacts your hormones and ovulation.

How to reintroduce carbohydrates

If your period has disappeared due to low carbohydrate intake, reintroducing carbs needs to be gradual to avoid bloating or digestive discomfort.

Start with one small serving of whole-food carbohydrates each day – like a few grapes or a spoonful of rice. If this is fine, gradually increase until you reach at least 120 grams daily, and perhaps working toward 200 grams over the following weeks.

Eat carbohydrates alongside protein and fat to slow glucose release and support stable energy.

For example, pair broccoli with eggs, rocket leaves with sardines, steamed greens with salmon.

Prioritise three regular meals daily – consistency signals safety to the hypothalamus and begins to restore the hormonal signals needed for ovulation.

It can take three to six months of sustained adequate eating for ovulation to return, sometimes longer. Your body needs repeated, reliable evidence that food is genuinely available before committing resources to reproduction.

Where you are in your cycle matters, once it returns. Women usually do better with more carbohydrates in the luteal phase (second half of the cycle), when the body is more sensitive to stress and requires additional energy to support progesterone production. 

Which carbohydrates are best

Not all carbs support hormonal health equally. Processed, high-glycaemic carbs (white bread, pastries, sweets, sugary drinks, flavoured yoghurts) all spike blood sugar and insulin, drive inflammation, and destabilise the hormonal environment. These do not restore ovulation.

Focus on whole-food carbohydrates:

• • Sweet potato – 25g per medium

• • Brown rice – 45g per cup cooked

• • Oats – 30g per cup cooked

• • Lentils – 40g per cup cooked

• • Quinoa – 35g per cup cooked

• • Butternut squash – 20g per cup cooked

• • Banana – 25g

• • Blueberries – 20g per cup

• • Apple – 20g

• • Sourdough bread (if tolerated) – 15g per slice

In practical terms, 120 grams daily looks like three balanced meals with generous servings of these carbs, plus protein, healthy fats. For women used to very low carb intake, it may feel unfamiliar at first, but consistency builds tolerance and supports ovulation recovery.

I do not work with active eating disorders, as this requires more specialist medical care. However, if you’re looking to restore or support your cycle from a more holistic perspective, I can help.

References

Chavarro JE, Rich‑Edwards JW, Rosner BA & Willett WC. Dietary carbohydrates and ovulatory infertility: a prospective study. Eur J Clin Nutr. 2009;63:78–86. PMCID: PMC3066074

Fumagalli M, Moltke I, Grarup N, et al. Greenlandic Inuit show genetic signatures of diet and climate adaptation. Science. 2015;349:1343–1347. Link

Kuhnlein HV & Receveur O. Dietary change and traditional food systems of indigenous peoples. Annu Rev Nutr. 2007;27:571–597. Link

Williams NI, et al. Hypothalamic amenorrhea: mechanisms and treatment. Endocr Rev. 2020;41:bnaa021.

Alwahab U., Pantalone KM & Burguera B. A ketogenic diet may restore fertility in women with polycystic ovary syndrome: a case series. AACE Clin Case Rep. 2018;4(5):e427–e431. DOI: 10.4158/ACCR‑2018‑0026

 Skoracka K., Ratajczak AE, Rychter AM, Dobrowolska A & Krela‑Kaźmierczak I. Female fertility and the nutritional approach: the most essential aspects. Adv Nutr. 2021;12(6):2372–2386. PMCID: PMC8634384