If you start looking up diet tricks to cure acne, you’ll find a thousand pieces of advice, from the helpful to the useless-but-harmless to the downright bizarre. But who has the time and energy to carefully engineer an entire anti-acne diet down to the milligrams of Omega-3 fats and the timing of your vitamin E supplements?
So, for the busy people, here’s the case for one single change that you can make to get the best return on investment: replace junk-food carbs with whole foods.
Acne, carbs, and blood sugar: the research
The short version is that recent research has increasingly highlighted a lot of highly refined carbs as a prime culprit in causing acne.
Population-level studies about who gets acne (people eating a typical Western diet) and who doesn’t (a few isolated hunter-gatherer populations) have been suggesting the role of diet in acne for at least 20 years now. Unsurprisingly, a lot of different aspects of diet have been linked to acne outbreaks: this review of studies up through 2016 discusses the evidence for omega-3 fats, antioxidants, some specific nutrients (vitamin A, zinc, and iodine), and dietary fiber. Other studies have shown that a Mediterranean diet (fish, nuts, olive oil, fruits, vegetables, low in sugar) is associated with lower acne rates.
But of all these potential culprits and cures, there’s particularly noteworthy and strong evidence for one single factor: highly refined and processed carbohydrates. Pretzels, goldfish crackers, tortilla chips, you know the drill.
In a study of acne sufferers from New York, one group of researchers found that participants with moderate or severe acne ate a higher absolute amount of carbohydrate, more carbs as a percentage of their diet, and more highly refined junk carbs. That’s an association and it can’t prove cause and effect, but intervention studies like this one have found that a diet low in refined carbs is actually a decent treatment for acne.
This intervention study used metformin (a diabetes drug) plus a diet “rich in fruits, vegetables and fish, low in carbohydrates” for 6 months and found that the intervention worked like a charm. Another study fed men with acne an experimental diet (high in protein, low in junk carbs) or a regular American diet for just 12 weeks (3 months) and found huge improvements in the experimental group.
A meta-analysis confirmed the association between dietary carbs and acne; the same meta-analysis also found that diets low in super refined carbs were effective interventions to treat acne. If taking out the refined carbs treats the problem, it’s pretty reasonable to assume that the refined carbs were at least part of the problem in the first place.
How does it work?
For the biologically curious, here’s how sugar and refined carbs make acne worse. (This study is free to read for those who want a deeper dive, and it’s the source for most of the bullet points below).
Insulin and IGF-1
Eating a lot of refined carbs increases the production of insulin (primer on insulin here) and Insulin-Like Growth Factor 1 (IGF-1).
- IGF-1 stimulates the production of sebum (that’s the waxy white stuff in the middle of acne lesions) and changes the type of fats in the sebum.
- Insulin and IGF-1 activate receptors for androgens (male sex hormones). Androgens regulate sebum production, so when cells are more sensitive to androgens, the result is more sebum and more acne.
Milk also contains a lot of IGF-1, which is one reason why the link between milk and acne has been studied pretty heavily. But interestingly, some research has found that this link is specific to low-fat dairy and skim milk, which has a lot more carbs relative to fat than full-fat dairy like butter. The researchers actually found no link between full-fat milk and acne.
On top of the insulin, eating a lot of refined carbs activates a signaling protein called mTORC1, which causes the sebaceous glands (which make sebum) to get bigger and produce more sebum, changes the type of bacteria living in hair follicles, and strengthens the immune/inflammatory reaction that ultimately produces visible acne.
it’s not just the short-term issues. Diets high in refined carbs also cause long-term problems. Most notably, eating a lot of refined carbs all the time is a great way to induce insulin resistance (which you can read about here if you don’t already know what it is). In insulin resistance, insulin levels stay chronically high because your body stops responding to the normal insulin signal – it’s like constantly yelling at someone because they don’t hear you when you talk at a normal volume. Research has fingered insulin resistance as a primary factor in acne development, because it just compounds all the hormonal effects of the high-carb diet.
Why focus on refined carbs?
OK, so a diet full of junk carbs contributes to acne. But there are so many problem foods out there: why focus just on refined carbs?
Because if you’re a typical person with limited time and energy for tweaking your diet, replacing junk carbs with real food is a quick and dirty way to get a lot done at once.
Getting rid of junk carbs lets your hormone levels normalize, so you’re not producing so much insulin and IGF-1 or messing up your mTORC1 signaling. It gets out the bad. But it also brings in the good, because you have to replace those carbs with something. If you used to have pasta with butter for dinner, you’re probably not going to ditch the pasta and eat only butter. You’re going to replace the pasta with something better, and there’s almost no way to lose with this:
- If you replace the junk carbs with vegetables, (that’s the recommendation in the classic Paleo template), you’ll get more fiber. Fiber helps prevent acne by modulating the gut microbiome (Seriously, this is a real thing! The linked article is free to read – there’s a lot of evidence that your gut health affects your skin).
- If you replace the junk carbs with protein-rich animal foods, you’ll enjoy less hunger and easier weight loss/muscle gain (if applicable). Fat loss and muscle gain both improve insulin sensitivity, which should be an extra help with acne issues.
- If you replace junk carbs with fish or seafood, you’ll get more omega-3s: these anti-inflammatory fats are great for fighting inflammatory problems like acne. Also, junk carbs are often soaked in junk oils, so by getting rid of cookies and cake, you’re also getting a lot of pro-inflammatory Omega-6 fats out of your life.
- If you replace junk carbs with almost any kind of real food, you’ll have a more nutrient-dense diet, full of all the important vitamins and minerals for good skin health like vitamin A, zinc, and iodine.
So: if you can only do one thing to help your skin, replace low-fiber, nutrient-poor junk carbs with whole foods. It cuts out a huge cause of harm and adds in a lot of the good stuff without making you weigh and measure and fuss over it all.
If you can do two things, dairy might be the next issue to consider, bearing in mind that low-fat dairy is likely worse than full-fat.