Signs of hair loss can be subtle at first, but if you're noticing more strands than normal in the shower drain or a thinner ponytail, that could be what's going on. Worrying about hair loss is understandable. Hair is part of our identity, and thinning can knock your confidence more than you'd expect.
The first port of call for most women when they experience hair loss is external: trying a new shampoo, rosemary oil, or a miracle cure recommended on Instagram. But as hair follicles are among the most metabolically active tissues in the body, they are often among the first things to be affected when there's an internal shift. Hair loss is rarely down to one thing, which is why understanding the cause is more important than reaching for the next product.
Why Hair Loss Happens
There are three phases to the hair growth cycle:
- Anagen – The active growth phase where follicles produce new hair.
- Catagen – During this transition stage, growth slows.
- Telogen – The resting phase when older hairs are released.
When your body is under stress, for example due to rapid weight loss, illness, or hormonal changes, more hairs can be pushed into the telogen phase, so you shed more than usual. This is known as telogen effluvium.
The Lag
Due to the length of the hair cycle, hair loss won't show up till 2–3 months after whatever caused it to start. So going on a crash diet in January would mean you don't see hair loss till March or April. That can mean women end up looking for a cause in the present that actually occurred many weeks ago.
Telogen Effluvium vs. Female Pattern Hair Loss
Telogen effluvium causes hair to shed evenly across the scalp and is usually temporary. Female pattern (androgenetic) hair loss is different. Triggered by genetics and hormones, it causes gradual follicle miniaturisation, and typically shows up as a widening parting and a loss in hair density over time.
The Nutritional Picture
What you eat shows up on your head before it shows anywhere else, as your hair cycle needs certain nutrients to function normally. These ones are the most important.
- Protein – Hair is formed of keratin, a structural protein, which needs a constant supply of amino acids to be repaired and replaced. If the body doesn't have enough amino acids, hair often suffers, as the body prioritises other areas that are essential for survival.
- Iron/Ferritin – Your follicles need both energy and oxygen. It's worth knowing that ferritin (the protein that stores iron in your body) can show up inside the normal range on blood tests, but still be too low to support a healthy hair cycle.
- Vitamin D – Supports follicle cycling and immune regulation, and is one of the two nutrients most consistently linked to hair health across the research. In the UK, the sun isn't strong enough from around October to March to provide Vitamin D, so levels often dip over winter.
- Zinc – A mineral that plays a role in protein synthesis and cell division. A clinical study that compared women with chronic telogen effluvium to those without found lower levels of zinc in the hair shedding group.
- Collagen – There is some promising research that found collagen peptides may prolong the hair growth phase. However, this study was conducted on follicles outside the body. It shows how collagen may support hair, but human research is still developing.
Even with a balanced diet, absorption matters. Inflammation and an imbalance in gut bacteria can impact nutrient uptake, which makes gut-friendly foods an important part of the picture.
Hormones and the Female Body
Hair shedding is often not down to something you've done wrong. Follicles are sensitive to hormones, that's just biology. It's widely known that hair often sheds postpartum, but the science is important. Oestrogen levels during pregnancy keep hair in the growth phase, then postpartum, the body releases a lot at the same time. Shedding is typically at its peak around the 3–4 month mark post-birth, and settles on its own by 6–12 months.
Perimenopause and menopause can also be a time when hair sheds more. As oestrogen declines, hair can grow more slowly, lose density, and change in texture. Hair loss is under-researched compared to other menopausal symptoms, but the psychological impact for women can be significant and often unrecognised.
An underactive or overactive thyroid can be responsible for shedding, as either disrupts the hair cycle. Another culprit is androgen sensitivity, a symptom of PMOS (until recently known as PCOS), which can cause hair to thin at the crown and grow in excess elsewhere in the body.
Dieting, Weight Loss, and Shedding
Weight loss itself is not a cause of shedding, but the speed of it, and the nutritional shortfall that comes with it, can be. If protein and calorie intake drop sharply, your body responds by redirecting resources away from non-essential processes. That includes hair, though due to the 2–3 month lag, this often occurs after weight loss rather than during it.
GLP-1 Medications and Restrictive Dieting
An increasingly popular choice for weight loss, many users of GLP-1 medications have reported hair shedding. While research is still emerging on the effects of these drugs, this may be due to rapid weight loss and reduced intake of nutrients. If you are on a GLP-1, protein and micronutrient rich meals matter even more, as your overall intake is significantly reduced. The same applies for appetite suppression, intermittent fasting, and weight cycling.
What Recovery Actually Looks Like
Nutrition is a good place to start for recovery. Getting adequate protein is the first step to maintain the supply of amino acids for the keratin in your hair. When diet is falling short, supplements like Iron + Folate, Multivitamins, or Collagen can help cover the foundations.
If the cause of hair loss is addressed, shedding usually slows by around 3 months. Regrowth typically appears after 6 months, with visible density changes showing by around 12 months. So if you make changes but don't see instant results, don't give up — your body just needs some time to get back on track.
When to See a Doctor
While a small increase in shedding is not usually cause for serious concern, there may be situations where seeing a doctor is the best course of action. If shedding worsens and is accompanied by other symptoms, such as constantly feeling cold, changes in menstruation, unexplained weight loss, scalp pain, or breathlessness, seek a medical opinion to rule out other causes like thyroid dysfunction, anaemia, or autoimmune conditions.
As previously mentioned, "your bloods are normal" doesn't always mean everything relevant to hair has been checked, so ask specifically about ferritin, thyroid function, vitamin D and zinc. Do not self-diagnose with supplements.
Your Hair Can Be an Indicator of Health
Hair is often one of the first ways your body signals that something has changed. Many factors can cause hair loss – nutrition, hormones, genetics, stress, or other conditions – so there's no single fix. Recovery does, unfortunately, require patience. Even if improvement is slow, it doesn't mean it's not happening. The most important thing is finding the underlying health cause for hair shedding, and taking action from there.
