Can Diet Affect Acne and Libido at the Same Time?

The key to understanding why diet could touch two systems as different as skin and the hormonal axis is insulin-like growth factor 1 (IGF-1) and insulin itself. Meals with a high glycemic index and glycemic load — ones that cause a fast, large rise in blood sugar — trigger an insulin spike, which in turn drives the liver to produce more IGF-1. IGF-1 acts on receptors present both in the skin's sebaceous glands and in the liver, where it regulates the production of sex hormone-binding globulin (SHBG).

In the skin, elevated IGF-1 increases keratinocyte proliferation in hair follicles and stimulates sebaceous glands to produce more sebum, while also increasing local activity of 5-alpha-reductase — the enzyme that converts testosterone into DHT, which binds more strongly to androgen receptors. It's this pathway, not "sugar" as such, that links high-glycemic eating to worsened acne. At the same time, insulin independently suppresses the liver's production of SHBG — and lower SHBG means more free, biologically active testosterone circulating in the blood, which could theoretically support libido, but in practice, alongside insulin resistance and obesity, the picture is considerably more complex, as we explain further below.

The strongest single piece of evidence linking diet to acne isn't a correlational observation — it's a randomized clinical trial, which is rarer in nutrition science than you might expect.

It's worth emphasizing the scale of this study — 43 participants is a small sample by evidence-based medicine standards, and the trial lasted 12 weeks, not years. It's solid but single evidence, not a final word on the topic. Even so, the result is consistent with the broader, largely observational literature linking a Western diet (highly processed, rich in refined sugar and dairy) to higher acne rates in populations going through dietary transition — a classic example being studies of populations traditionally not eating a Western diet (such as residents of Papua New Guinea or Paraguay), where acne was essentially absent under a traditional way of eating.

Dairy, and skim milk in particular, is a second dietary factor linked to acne in several large cohort studies, independent of glycemic index — among them work by the Adebamowo team at the Harvard School of Public Health. Interestingly, the association was stronger for skim milk than for whole milk, suggesting the mechanism isn't purely about fat or calorie content, but rather about hormones and growth factors naturally present in milk — including IGF-1 and hormone precursors that a cow's body produces during pregnancy and that end up in milk regardless of its fat content.

This is still mostly observational evidence, not as strong as the randomized trial described above, so the causal link is plausible but not fully proven mechanistically for every patient. The practical takeaway isn't "eliminate dairy entirely," but rather: if you have stubborn acne resistant to standard topical treatment, an experimental, temporary reduction in dairy (especially milk) for 4-8 weeks is a cheap, low-risk intervention worth trying alongside dermatological treatment, not instead of it.

On the libido side, the evidence is scarcer and less direct than for acne — there's no trial analogous to Smith and colleagues' randomized study that measured libido as its main endpoint for a low-glycemic diet. What does exist is research showing that highly processed diets rich in refined sugar correlate with lower SHBG and metabolic syndrome features, while diets rich in fiber and with a lower glycemic load are linked to higher SHBG in population and weight-loss intervention studies.

The catch is that a rise in SHBG isn't unambiguously good news for libido — higher SHBG means less free testosterone, so it could theoretically even reduce the availability of biologically active hormone. What genuinely links diet to libido for most men isn't a direct manipulation of SHBG, but indirect effects: weight loss in people who are overweight (visceral obesity is one of the most well-documented, reversible factors lowering total testosterone), better sleep quality from avoiding late, heavy meals, and more stable energy and mood — all of which affect sex drive on their own, independent of the numbers on a blood test.

It's worth being honest here: for most men with adult acne and most men with reduced libido, diet is at most one of several coexisting factors, not the main culprit. Hormonal acne is often driven mainly by chronic stress, genetic androgen-receptor sensitivity, or unsuitable skincare — a topic we cover in more depth in our article on recognizing hormonal acne. A drop in libido just as often stems from sleep deprivation, depression, medication (especially SSRIs), alcohol, or relationship dynamics, regardless of what ends up on your plate.

Diet is neither a miracle cure for acne and libido nor a factor you can safely ignore. It's one of the few genuinely shared denominators for two seemingly independent problems, backed by a solid, if small, RCT on the acne side and weaker, mostly indirect evidence on the libido side. It's worth treating a diet change as one of several parallel steps — alongside proper skincare, sleep hygiene, and, if symptoms persist, a medical consultation — not as the sole solution your entire strategy rests on.