Oily skin — driven by excess sebum production from sebaceous glands — affects a significant proportion of people, particularly during adolescence and young adulthood but also persisting into later life. While genetics and hormones are the primary determinants of sebum production, diet has a measurable influence through its effects on hormonal signalling, inflammation, and the hormonal axes that regulate sebaceous gland activity. Understanding the dietary connections allows for meaningful management alongside topical skincare.
The Glycaemic Index and Sebum
High-glycaemic index (GI) foods — those that cause rapid blood sugar spikes — have the strongest dietary evidence for worsening oily skin and acne. The mechanism: rapid blood glucose elevation triggers insulin release, which activates insulin-like growth factor-1 (IGF-1), which directly stimulates sebaceous gland activity and sebum production. Multiple randomised controlled trials have demonstrated that switching from high-GI to low-GI dietary patterns significantly reduces sebum production and acne lesion counts within 12 weeks.
High-GI foods to moderate: white bread, white rice, sugary drinks, cakes, biscuits, pastries, and highly processed breakfast cereals. Lower-GI alternatives: whole grains (oats, brown rice, wholegrain bread), legumes, most vegetables, and fruits with their fibre intact. The NHS Eatwell Guide supports a lower-GI dietary pattern as part of healthy eating generally — the skin benefits are an additional dividend.
Dairy and Sebum: The Emerging Evidence
Several large observational studies have found associations between dairy consumption (particularly skimmed milk) and increased acne and oily skin, though causation has not been definitively established. The proposed mechanisms include the hormonal content of milk (bovine IGF-1 and precursors to dihydrotestosterone) and milk's glycaemic effect despite its low GI (milk strongly stimulates insulin release through mechanisms beyond glycaemic index). The British Association of Dermatologists notes the association as requiring further research but supports dietary trials in acne-prone individuals.
For people with oily skin or acne who consume significant dairy, a 6–8 week trial of reducing dairy consumption provides a personal test of whether dairy is a significant driver — any improvements in skin oiliness suggest dairy is a relevant factor for that individual.
Omega-3s: The Counter-Sebum Effect
Omega-3 fatty acids have anti-inflammatory and anti-androgenic properties that reduce the stimulation of sebaceous glands. Several trials have demonstrated reduction in sebum production and acne with omega-3 supplementation. Dietary sources: oily fish (salmon, mackerel, sardines) twice weekly, walnuts, flaxseed, and chia seeds. The balance between omega-6 and omega-3 matters — reducing processed foods that are high in omega-6 while increasing omega-3 sources shifts the ratio in the sebum-reducing direction.
Zinc and Sebum Regulation
Zinc reduces 5-alpha-reductase activity — the enzyme that converts testosterone to the more potent dihydrotestosterone (DHT) that stimulates sebaceous glands. Zinc deficiency is associated with increased sebum production, and zinc supplementation has evidence for reducing sebum production and acne in deficient individuals. Dietary sources: pumpkin seeds, oysters, red meat, lentils, and cashews.
The Practical Dietary Approach
For oily skin management through diet: switch to low-GI carbohydrates; reduce refined sugars and ultra-processed foods; trial a period of reduced dairy; increase oily fish to twice weekly; add zinc-rich foods; and increase antioxidant-rich vegetables. These changes address the hormonal and inflammatory drivers of excess sebum simultaneously and are consistent with a generally healthy diet.
For more on skin and diet, see our acne and diet guide and our skin barrier nutrition guide. For clinical skin concerns, consult a dermatologist — the British Association of Dermatologists has a patient information library.
Supporting Your Health Through Daily Nutrition
Understanding the principles covered in this article is valuable — but applying them consistently through daily food choices is where the real benefit comes. For London office workers, the quality of the daily work lunch is one of the most controllable nutritional variables in the day. A fresh, balanced, nutritious lunch delivered to your desk removes one decision from a demanding schedule and ensures a consistently good nutritional foundation.
Vanda's Kitchen near St Paul's Cathedral EC4 delivers certified halal, 100% nut-free, freshly prepared corporate catering across the City of London and central London. Our Filipino-inspired menu is built around lean proteins, fresh vegetables, and complex carbohydrates — the nutritional combination that supports energy, performance, and health throughout the working day. Every item we produce carries full allergen labelling in compliance with Natasha's Law, and our entire kitchen is independently certified halal by the Halal Friendly List.
Our Selfridges Food Hall presence confirms the quality standard we maintain. For London teams wanting consistently nutritious, genuinely delicious, allergen-safe daily lunches, Vanda's Kitchen is the straightforward answer. View our team lunch options, WhatsApp us for a same-day response, or send an enquiry. Read our healthy office lunch delivery guide for more on what we offer and how our delivery works.
Frequently asked questions
How long does it take to see changes in skin oiliness after switching to a lower-GI diet?
Randomised controlled trials on low-GI dietary interventions for acne and sebum reduction typically show measurable changes within 12 weeks. Individual responses vary, and some people notice improvements in skin texture and oiliness within four to six weeks of reducing high-GI foods. Consistency matters more than speed — sporadic dietary changes produce inconsistent skin responses.
Does drinking more water reduce oily skin?
Water intake affects skin hydration rather than sebum production, and the two are different things. Oily skin is driven by sebaceous gland activity, not dehydration — you can have oily skin and be dehydrated simultaneously. Adequate hydration supports overall skin health and barrier function, but it does not directly reduce sebum production through any established mechanism.
Are there specific cooking oils that worsen oily skin?
Oils high in omega-6 fatty acids — particularly refined vegetable oils such as sunflower, corn, and soybean oil — consumed in excess relative to omega-3 intake shift the omega-6 to omega-3 ratio in a pro-inflammatory direction, which can stimulate sebaceous gland activity. Extra virgin olive oil and oily fish as primary fat sources support a better omega-3 to omega-6 balance that may reduce sebum production over time.
Can cutting out sugar completely clear oily skin?
Completely eliminating sugar is neither necessary nor sustainable for most people. The evidence supports reducing high-GI foods — sugary drinks, confectionery, white refined carbohydrates — rather than eliminating all sugar from the diet. Replacing these with lower-GI alternatives provides the insulin-stabilising effect that reduces sebaceous gland stimulation. Small amounts of sugar in a generally low-GI diet are unlikely to drive significant sebum production.
Is oily skin made worse by greasy or fried foods directly, or is the effect indirect through glycaemic mechanisms?
The relationship is primarily indirect. Dietary fat itself does not directly increase sebum production — sebum composition and volume are regulated hormonally, not by matching dietary fat intake. However, high-fat meals slow gastric emptying and raise insulin more than their GI would suggest, and repeated large high-fat meals contribute to the insulin and IGF-1 signalling that drives sebaceous gland activity. The total dietary pattern matters more than individual foods.