If you've been fighting breakouts for years — trying every cleanser, spot treatment, and skincare routine — and nothing is really working, there's a good chance you've been solving the wrong problem. Acne is not primarily a skin problem. It's an internal one, and the skin is just where it surfaces.
I've talked to so many women who have tried everything topically and are still breaking out. And almost every time, once we start looking at what's happening on the inside — diet, gut health, inflammation — the pattern becomes clear. The breakouts were a symptom all along.
Here are the most common dietary drivers of acne, backed by research, and what to do about each one.
High-Glycaemic Foods and the Insulin Connection
This is probably the most well-established dietary link to acne in the research. When you eat foods that spike blood sugar rapidly — white bread, sugary drinks, processed snacks, white rice — your body releases a surge of insulin. That insulin spike triggers the production of IGF-1 (insulin-like growth factor 1), which in turn stimulates sebaceous glands to produce more sebum and accelerates skin cell turnover. The result: more oil, more clogged pores, more breakouts.
Multiple studies have shown that people who switch to a low-glycaemic diet experience significant reductions in acne — not because of some miraculous ingredient, but simply because blood sugar is more stable. Swap refined carbs for whole grains, legumes, and vegetables. The difference can be noticeable within a few weeks.
"Acne is not primarily a skin problem. It's an internal one — and the skin is just where it surfaces."
Dairy: The Complicated Relationship
Dairy and acne is a nuanced topic, but the evidence is hard to ignore. Several large studies have found an association between milk consumption — especially skim milk — and increased acne prevalence. The mechanism is thought to involve hormones naturally present in cow's milk (including IGF-1 and androgens), which can stimulate sebum production and promote the conditions that lead to breakouts.
This doesn't mean all dairy is problematic for everyone. Full-fat dairy appears to have a weaker association than skim, and fermented dairy like yoghurt and kefir seems to be less problematic — possibly because the fermentation process modifies the hormonal compounds. If you're breaking out consistently and consume a lot of milk or skim dairy, try reducing it for 4–6 weeks and see what happens.
Gut Dysbiosis and the Skin-Gut Axis
Your gut microbiome and your skin are in constant communication. When the balance of bacteria in your gut is disrupted — through a poor diet, antibiotics, chronic stress, or alcohol — it can lead to increased intestinal permeability (commonly called leaky gut), where bacterial byproducts leak into the bloodstream and trigger low-grade systemic inflammation. That inflammation shows up everywhere, including the skin.
Research has found that people with acne tend to have different gut microbiome compositions than people with clear skin, and that improving gut health through diet and probiotics can improve skin outcomes. Eating more fermented foods (kefir, kimchi, sauerkraut), prebiotic fibre (garlic, onion, oats), and reducing ultra-processed foods is one of the most impactful things you can do for both gut and skin.
A 2021 review in the journal Nutrients found that probiotic supplementation reduced acne lesion counts in multiple clinical trials — supporting the gut-skin connection as a real and actionable pathway.
Nutritional Deficiencies That Drive Breakouts
Three nutrients in particular are closely tied to acne when deficient:
- Zinc — regulates sebum production, has anti-inflammatory properties, and supports wound healing. Many people with acne are zinc deficient. Find it in oysters, pumpkin seeds, beef, and walnuts.
- Vitamin A — regulates skin cell turnover and reduces the build-up of dead cells that block pores. Retinoids (a derivative of vitamin A) are one of the most prescribed acne treatments for a reason. Food sources include sweet potato, liver, and eggs.
- Omega-3 fatty acids — reduce the inflammatory response that drives acne. Most people eat far too little omega-3 relative to omega-6. Wild salmon, sardines, walnuts, and flaxseeds are your best sources.
Sugar and Inflammation
Beyond the glycaemic response, excess sugar promotes a process called glycation — where sugar molecules bind to proteins like collagen and elastin, damaging them and triggering an inflammatory cascade. Chronic inflammation is one of the key underlying drivers of acne, and sugar is one of its most reliable promoters. Reducing added sugar is one of the highest-leverage dietary changes for skin health overall.
What to Actually Do
Rather than elimination diets that feel restrictive and unsustainable, I recommend a food-first addition approach: crowd out the problematic foods by adding more of the good ones. Here's where to start:
- Add omega-3s daily — wild salmon 3x per week, walnuts as a snack
- Swap refined carbs for whole food sources — oats, sweet potato, legumes
- Add a daily serve of fermented food — kefir, yoghurt, kimchi, or sauerkraut
- Reduce added sugar — especially in drinks, sauces, and packaged foods
- Trial a dairy reduction for 4–6 weeks if breakouts are persistent
- Consider a zinc supplement short-term if deficiency is suspected
The skin responds to consistent dietary changes over 6–12 weeks. It won't happen overnight, but when it does shift, it tends to be meaningful and lasting — not just a suppression of symptoms. You're addressing the root, not covering up the signal.