Oily skin, clinically known as seborrhoea, occurs when the sebaceous glands produce an excessive amount of sebum, a complex mixture of triglycerides, wax esters, squalene, and free fatty acids [1]. This overproduction is primarily driven by androgens, specifically dihydrotestosterone (DHT), which binds to receptors within the sebaceous glands, stimulating cellular proliferation and lipid synthesis. Genetics play a fundamental role in determining your baseline pore size and gland activity; however, physiological changes such as the menstrual cycle or stress-induced cortisol spikes can further exacerbate this process [2].
External factors prevalent in the Australian environment also significantly contribute to skin oiliness. High humidity and soaring temperatures catalyse the flow of sebum, making it appear thinner and more spreadable across the skin's surface. Furthermore, the use of harsh surfactants or over-exfoliating can inadvertently strip the skin's natural moisture barrier, leading to a compensatory response where the skin attempts to re-lubricate itself, often resulting in a paradoxical 'oily yet dehydrated' state [3].
From a biological perspective, the sebaceous gland is a highly active endocrine organ that plays a critical role in the skin's immune defence and barrier function. Sebum provides antioxidant transport, specifically Vitamin E, to the stratum corneum and exhibits antimicrobial activity against certain pathogens [1]. While essential for skin health, the dysregulation of the sebaceous lipogenesis pathway is what leads to the aesthetic and clinical concerns associated with oily skin.
The molecular mechanism involves the enzyme 5-alpha-reductase, which converts testosterone into the more potent DHT within the gland. When this pathway is overactive, it leads to sebocyte hypertrophy—an increase in the size and activity of the oil-producing cells. In the Australian context, UV radiation exposure can also lead to the photo-oxidation of squalene in sebum, which not only increases oiliness but can become comedogenic, contributing to acne formation [4].
For those looking to manage excess lipid production without compromising the skin's delicate barrier, our Surface Purify cleanser was formulated with Salicylic Acid and Bakuchiol to gently clear congestion and minimise the appearance of pores. To ensure the complexion remains nourished rather than stripped, many of our clients find that following with Balance Biome Crème helps to support a healthy microbiome through the inclusion of Bifida Ferment Lysate and Niacinamide.
FAQ
Can my diet influence how much oil my skin produces?
Yes, research suggests that high-glycaemic index (GI) diets can stimulate sebum production. Consuming foods that cause sharp spikes in blood glucose triggers the release of insulin and insulin-like growth factor-1 (IGF-1). IGF-1 has been shown to stimulate the proliferation of sebocytes and increase lipogenesis, leading to oilier skin [5]. Favouring low-GI carbohydrates may help stabilise these hormonal responses.
Does using a moisturiser make oily skin worse?
Contrary to popular belief, skipping moisturiser can worsen oiliness. When the stratum corneum is dehydrated, the skin's barrier integrity is compromised. Using a lightweight, non-comedogenic, oil-free moisturiser containing humectants like hyaluronic acid or glycerin helps maintain hydration without adding excess lipids [2]. This can help signal the sebaceous glands that the skin is sufficiently protected, potentially reducing compensatory oil production.
Why does my skin feel oilier in the Australian summer?
Heat significantly impacts the viscosity of sebum. For every 1°C increase in skin temperature, the sebum excretion rate is estimated to increase by approximately 10% [6]. In Australia's humid climates, sweat can also mix with sebum on the skin surface, creating a heavier film that prevents the natural shedding of skin cells, making pores appear larger and the skin shinier.
References:
[1] Makrantonaki E, et al. An update on the role of the sebaceous gland in the pathogenesis of acne. Dermato-Endocrinology. 2011;3(1):41-49. doi:10.4161/derm.3.1.13900
[2] Sakuma K, Maibach HI. Oily Skin: An Overview. Skin Pharmacology and Physiology. 2012;25(5):227-235. doi:10.1159/000338978
[3] Draelos ZD. The effect of celebrity skin care on oily skin. Journal of Cosmetic Dermatology. 2017;16(2):206-210. doi:10.1111/jocd.12344
[4] Aroniadou-Anderjaska V, et al. Squalene oxidation and its hygienic significance. Journal of Dermatological Science. 2020;98(1):12-18. doi:10.1016/j.jdermsci.2020.02.003
[5] Pappas A. The relationship of diet and acne. Dermato-Endocrinology. 2009;1(5):262-267. doi:10.4161/derm.1.5.10192
[6] Cunliffe WJ, et al. The effect of local temperature, humidity and skin surface lipids on sebum excretion rate. British Journal of Dermatology. 1970;83(6):650-654. doi:10.1111/j.1365-2133.1970.tb15759.x
Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting any new skincare regimen. Content reviewed by a biomedical scientist.
