The Ultimate Guide to Hormonal Acne

Cornerstone Hormones - Insulin and IGF-1

Insulin is the cornerstone, and often the missing piece, in hormonal acne. It affects acne by making the skin more sensitive to other hormones.

Insulin and IGF-1 are the cornerstones of hormonal acne. Eating too much sugar or other carbohydrates results in a spike in insulin levels; insulin, in turn, triggers a cascading hormonal reaction that floods the bloodstream with DHEA and other androgen precursor hormones. The skin converts these hormones into testosterone and DHT, which increase oil production and results in acne.

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Insulin is a hormone produced by the pancreas that allows your body to use carbohydrates for energy. When you eat carbohydrates, they are broken down into glucose in the digestive system and then absorbed into bloodstream. Insulin allows the glucose molecules to enter into cells where they are used for energy.

The more carbohydrates you eat, the more insulin the pancreas has to release to maintain stable blood sugar levels. Insulin is also released after eating dairy products.

Insulin-like growth factor 1 is a growth hormone with a similar molecular structure to insulin.

Glycemic index, or GI, ranks carbohydrates on a scale of 1 to 100 based on how much they increase blood sugar levels after eating. A food with a high GI results in a rapid increase in blood sugar and insulin levels – whereas a food with low GI value results in a slower, and overall smaller, increase in blood sugar and insulin levels.

As a rule of thumb, white and processed carbohydrates have a high GI value, whereas unprocessed carbohydrates are lower in the GI scale.

The more carbohydrates you eat, the more insulin the pancreas has to release to maintain stable blood sugar levels.

Insulin-like growth factor 1 is a growth hormone with a similar molecular structure to insulin.

How insulin and IGF-1 cause acne

Insulin and IGF-1 affect acne in several ways.

  • Like androgens, they directly stimulate skin cells to produce more sebum.
  • High insulin and IGF-1 stimulate the release of DHEA from the adrenals – several studies have shown a correlation between the two hormones.
  • They also inhibit the release of sex hormone binding globulin (SHBG) from the liver. The vast majority of testosterone in the blood is bound to SHBG, and while bound to SHBG testosterone is biologically inactive.
  • Insulin and IGF-1 regulate the conversion of androgen precursors into testosterone and DHT in the skin.

Supplementing with IGF-1 increases testosterone levels and causes acne in majority of women

Much like androgens, IGF-1 is required for the development of acne. A 2011 study on Laron syndrome patients, who are deficient in IGF-1, showed very low rates of acne. Furthermore, a large dose of IGF-1 resulted in acne and hyperandrogenism in half of the female patients, but acne disappeared after lowering the IGF-1 dose.

One paper describing cases of women with Laron syndrome clearly illustrated the role IGF-1 plays in stimulating androgen release and causation of acne.

During the administration of IGF-I in what we subsequently discovered to be excessively high doses, four out of the six developed, in a progressive manner, increased serum levels of testosterone, and D4-androstenedione which led to clinical signs of oligomenorrhoea and acne.

Klinger, B., Anin, S., Silbergeld, A., Eshet, R. & Laron, Z. Development of hyperandrogenism during treatment with insulin-like growth factor-I (IGF-I) in female patients with Laron syndrome. Clin. Endocrinol. (Oxf) 48, 81–7 (1998).

For all these reasons, studies have found that IGF-1 levels correlate with sebum production, skin pore size, and acne lesion count in women. In men, IGF-1 correlates with some of the androgen hormones. (source).

IGF-1 levels correlated with pore size, oiliness and acne in women

The link between insulin and IGF-1

According to Wikipedia, approximately 98% of the IGF-1 is bound to insulin-like growth factor binding proteins (IGFBP). As it was with androgens, bound IGF-1 is not bioactive. It circulates in your blood without affecting anything. It’s there as a reserve that the body can quickly draw from.

Chronically high insulin levels, such as what happens when one regularly eats sugar, processed carbohydrates or dairy products, stimulates the release of IGF-1 from the liver and reduces the secretion of IGFBP (source).

Let’s recap a bit. High insulin levels stimulates the release of IGF-1 and blocks the release of IGF binding protein; the net effect of this is a significant increase in bioactive IGF-1 in the blood. IGF-1 in turn stimulates the release of DHEA from the liver and inhibits the release of sex hormone binding globulins. Again, the net effect is a significant increase in bioavailable androgens in the blood. DHEA makes its way into the skin where it’s converted into testosterone and DHT; this conversion is super charged thanks to high insulin and IGF-1 levels. These hormones stimulate the skin to produce more oil, which makes it much more likely that you get acne.

In other words, insulin triggers a cascading hormonal reaction that results in the skin producing more oil and increased risk of acne. This is why every study in the last 20 years that has looked at the relationship between diet and acne shows that dietary interventions that reduce sugar, processed carbohydrates and dairy products also reduce acne (source).

All this fits in nicely with what we know about acne and insulin resistance.

Studies linking acne to insulin-spiking foods

  • Smith et al. showed high protein, low glycemic index diet reduced acne and androgen levels. 
  • Another study by Smith et al. showed similar results.
  • Yet another study by Smith et al. showed that putting acne patients on a low glycemic index diet reduces acne.
  • Reynolds et al. showed that diet that’s moderately high in protein and somewhat restrict carbohydrates reduces acne – regardless of the overall glycemic index.
  • Kwon et al. put 17 people with acne on low GI diet and another 15 acne patients were asked to continue their normal diet. After 10 weeks, the group on low GI diet had 27% less acne.
  • In two separate studies in 2006 and 2008 Adebamow et al. showed that teenagers who drink more milk have a higher risk of getting acne. 
  • Landro et al. showed those eating more than 3 portions of dairy per week were 78% more likely to have acne than those who didn’t consume any dairy.
  • Ismail et al. showed that those with acne ate more processed carbohydrates and ice cream than their peers without acne.
  • Skroza et al. showed sticking to mediterranean-style diet reduced the risk of acne.
  • Okoro et al. showed that acne was more common among Nigerian teens who had dairy or cake daily than those who didn’t. 

Every study in the last 20 years that has looked at the relationship between diet and acne shows that diets that reduce sugar, processed carbohydrates, and dairy products also reduce acne

Insulin resistance

Insulin resistance is a condition in which the cells’ response to insulin is hindered, and the pancreas has to compensate by releasing more insulin.

A 2012 Italian study looked at 22 young men with acne and compared their blood sugar metabolism to 22 healthy controls. This table shows the results.

These data clearly show insulin resistance in acne patients. While the difference in blood glucose (blood sugar) levels is minimal, acne patients require significantly higher insulin levels to achieve them. The difference in 120-minutes oral glucose tolerance tests (OGTT) is especially striking, with acne patients showing almost 400% higher insulin levels. Acne patients also had about 10% higher IGF-1 levels.

To date, five studies have looked at whether people with acne (men and women) have insulin resistance. 4 of the 5 showed those with acne are insulin resistant and/or have higher insulin levels than comparable people without acne.

This, again, explains why diets that reduce sugar and high glycemic index carbohydrates are so effective against acne. Eating less sugar and processed carbohydrates means the pancreas has to pump out less insulin to keep blood sugar levels under control.