Sugar and Acne: Does a High-Glycemic Diet Cause Breakouts?

A diet heavy in sugar and fast-digesting carbs may make acne worse for some people, though sugar alone doesn't start it. In two randomized trials, young people with acne who switched to a low-glycemic-load diet for 10 to 12 weeks had fewer lesions than control groups. The likely route is insulin: blood sugar spikes raise insulin and IGF-1, which can increase oil and androgen activity.

Below we explain glycemic index and glycemic load, walk through the trials and the hormone pathway, look at what chocolate studies found, and lay out a practical lower-GI swap list. Sugar's effect on collagen and wrinkles is a separate topic, covered in our article on sugar and skin aging.

Does sugar cause acne?

Sugar is one possible aggravating factor, and the evidence is moderate at best. The American Academy of Dermatology says findings from small studies suggest a low-glycemic diet may reduce the amount of acne you have, while other studies have found no connection and more research is needed. Acne still starts when pores become clogged, as the AAD's page on what causes acne explains, and hormones that enlarge oil glands play a big part. Diet may turn the volume up or down for some people.

Population data points the same way. A 2020 study of 24,452 French adults in JAMA Dermatology found current acne was associated with fatty and sugary products (adjusted odds ratio 1.54) and sugary drinks (1.18). It was a cross-sectional survey with self-reported acne, so it can't show cause. An older 2002 report in Archives of Dermatology found no acne among 1,200 Kitavan Islanders in Papua New Guinea or 115 Aché hunter-gatherers in Paraguay, whose traditional diets contain few refined carbohydrates. Genes, lifestyle and many other factors differ between those groups and Western teenagers, so the comparison raises a question more than it answers one.

What is the difference between glycemic index and glycemic load?

Glycemic index (GI) measures how quickly a carbohydrate food raises blood sugar compared with pure glucose, which scores 100; glycemic load (GL) also accounts for how much carbohydrate a normal serving contains. MedlinePlus, the NIH's consumer health site, classes foods scoring 0 to 55 as low GI and 70 or higher as high GI, and notes that portion size and the amount of carbohydrate still matter. GL is the number the acne trials targeted, because it reflects what a whole meal does to blood sugar.

Using MedlinePlus's examples, lower-GL eating usually means:

• Swapping white bread, bagels, white rice, potatoes and most processed cereals (all high GI) for steel-cut or rolled oats, barley, bulgur, quinoa, legumes and beans (low GI).
• Choosing whole fruit over juice; processed foods such as fruit juice have a higher GI than the whole food.
• Pairing a high-GI food with low-GI foods, since foods higher in fat or fiber tend to have a lower GI.
• Cutting sugary drinks. The AAD's diet page lists milkshakes among high-glycemic foods.

How does a high-glycemic diet lead to breakouts?

The proposed chain runs from blood sugar to insulin to hormones to oil glands. DermNet describes it this way: foods that raise insulin have a high glycemic index, and insulin can increase acne. The steps researchers have measured look like this:

1. Insulin rises. High-GL meals cause larger insulin spikes, and over time can reduce insulin sensitivity.
2. IGF-1 activity rises and binding proteins fall. In a 7-day controlled feeding study of 12 teenage boys, the low-GL group improved insulin resistance scores and increased IGF binding proteins 1 and 3, which keep IGF-1 in check.
3. Androgens become more available. In the same study, sex hormone binding globulin (SHBG), which mops up free testosterone, dropped in the high-GL group. A 12-week trial in JAAD found the low-GL diet reduced the free androgen index.
4. Oil glands respond. In a 10-week Korean trial, skin biopsies from the low-GL group showed smaller sebaceous glands, less inflammation and lower levels of SREBP-1, a protein that drives oil production.

This is the same insulin and IGF-1 pathway behind the milk theory, which we cover in does dairy cause acne. Androgen sensitivity is also why breakouts often cluster on the jaw and track the menstrual cycle; see hormonal acne for that side of the picture.

What did the low-glycemic diet trials find?

Two randomized trials found that lowering glycemic load reduced acne lesions over about three months. Both were small and short.

The low-GL diet in the Australian trial got 25% of energy from protein and 45% from low-GI carbohydrates. That's a specific, fairly high-protein pattern, so the results may not apply to someone who just skips dessert. Still, lesion counts fell in both studies, and that's more than most diet claims can show.

Does chocolate cause acne?

Chocolate may worsen acne in some acne-prone people, and the old "it's a myth" verdict looks less certain than it did. Two small trials in men point that way:

• A double-blind, placebo-controlled study of 14 men aged 18-35 with a history of acne gave capsules of unsweetened 100% cocoa, gelatin placebo or a mix. Lesion counts rose significantly by day 4 and day 7, and more cocoa was loosely correlated with more lesions. Because the capsules held pure cocoa, sugar wasn't the variable.
• In a 4-week Thai study, 25 acne-prone men ate 25 g of 99% dark chocolate a day. Acne scores and counts of comedones and inflamed papules rose significantly within 2 weeks.

Neither study included women, and both were tiny. Some researchers suggest that compounds in chocolate itself raise insulin; DermNet notes that caffeine, theobromine and serotonin found in chocolate may increase insulin production. A milk chocolate bar adds sugar and milk on top, which are suspects in their own right. If chocolate seems to set you off, it's worth testing the same way as any other food.

Which foods are most linked to acne?

The most consistent links are with high-glycemic foods and milk, with weaker evidence for chocolate. This summary sorts the main suspects by evidence strength:

How do I try a low-glycemic diet for acne?

Treat it as a 10-12 week experiment, because that's how long the trials ran before they measured a difference. Short tests of a week or two can't show much.

1. Take baseline photos. Same light, same angle, clean face, two or three times a week for one week before you change anything.
2. Cut sugary drinks first. Soda, sweet coffee drinks, juice and energy drinks are the easiest high-GL source to remove.
3. Swap staples. Change white bread, white rice and sweet cereal to whole grains, oats, legumes or extra vegetables.
4. Add protein to carb meals. Eggs, fish, chicken, tofu or beans with each main meal, closer to the trial diet's pattern.
5. Keep your skincare steady. Don't start or stop an acne treatment mid-test. A basic plan like our routine for acne-prone skin works alongside diet changes.
6. Compare at week 6 and week 12. Count new inflamed spots, not leftover marks.

If you have diabetes, take glucose-lowering medicine, are pregnant, or are a teen, check with your doctor or a dietitian before changing how you eat. Extreme sugar cutting isn't the goal; steady, lower-GL meals are.

Can a selfie scan help you see if diet changes work?

Diet effects on skin are slow, so you need a record you can trust. Pori turns a selfie into an overall skin score from 0 to 100 with a breakdown that includes Pores & Texture and Overall health. Its skin diary logs diet, sleep, water and stress next to each scan, and before/after comparison and progress charts show whether weeks of lower-GL eating look different from your baseline. Our wider guide on how lifestyle affects your skin covers the other factors worth logging.

Pori tracks how your skin looks; it isn't a diagnosis and can't tell you which kind of acne you have.

When is diet not enough?

Diet is an add-on to acne treatment, never a replacement. The 2024 AAD guidelines of care give strong recommendations for benzoyl peroxide, topical retinoids, topical antibiotics and oral doxycycline, and for isotretinoin in severe or scarring acne. The NHS says to see a doctor if spots are deep, painful or causing scars, if self-treatment isn't working, or if acne is affecting your mental health.