How does sugar cause acne? - the acne diet

Acne, also called acne vulgaris, has several causes that work together. The main reasons people get acne are:

• The skin often produces too much oil (sebum), usually due to hormone changes. Oil and dead skin cells can block hair follicles.
•  Extra androgens, which are male sex hormones, can worsen acne. This is one of the leading causes of acne in teenagers and adult acne.
• An imbalance in skin bacteria, called Propionibacterium acnes (P. acnes), digests skin oil and triggers blackheads and inflammation.

In recent years, it has been found that certain foods, such as dairy, sugar, and grains, can also cause pimples. A 2021 review of 53 studies found that eating foods high in sugar, dairy products, and fatty foods worsens acne.

Meanwhile, eating fewer carbs and more omega-3 fats helps protect against acne. Researchers found a link between milk and dairy and acne, but they remain unsure if the type of milk (low-fat, skim, or whole) matters.

The American Academy of Dermatology found people who drink cow's milk (of any kind) have a greater chance of developing acne than those who do not.

How does sugar cause acne?

Eating a lot of sugar or carbs boosts your body's levels of insulin (a hormone that helps regulate blood sugar) and another hormone called IGF-1 (insulin-like growth factor 1). High IGF-1 can lead to weight gain, type 2 diabetes, and also:

• High IGF-1 turns more testosterone into dihydrotestosterone, which signals the skin to produce more oil. This extra oil feeds the bacteria, allowing them to grow.
• IGF-1 enlarges oil glands in the skin. More oil and bigger glands cause whiteheads, which then turn into blackheads when exposed to air.
• IGF-1 also stimulates skin cell proliferation, which can lead to more acne.

A 2007 study found that people who reduced their sugar intake for 12 weeks developed fewer acne spots, lower hormone levels, and higher levels of a protein that helps control insulin.

This leads to a common question: Was Grandma right about eating greasy food and getting pimples?

Recent research shows that eating lots of sugary or starchy foods worsens acne. If your  treatment is not responding, changing your diet can help. Alongside sugar, dairy may contribute to acne, so eating foods like flavoured yogurt may worsen pimples.

How do I know which foods are causing my acne?

The best approach is to use the elimination diet by cutting back one food group at a time. For example, cut out dairy or switching from animal based dairy to plant based dairy for at least one month. Move onto the second food group which may include sugars and foods high in carbohydrates. Some people find keeping a food diary, making notes in your phone and progress photos also helps to track your findings which are personalised to you. 

References: 

1. Dall’Oglio, F et al (2021). "Diet and acne: review of the evidence from 2009 to 2020." International Journal of Dermatology. First published: 18 January 2021. Accessed: https://doi.org/10.1111/ijd.15390
2. "Can the Right Diet Get Rid of Acne?" American Academy of Dermatology Association. Accessed 3rd August, 2022.
3. Smith, R et al. "The effect of a high-protein, low glycemic-load diet vs a convention, high glycemic-load diet on biochemical parameters associated with acne vulgaris: a randomised, investigator-masked, controlled trial." Journal of American Academy Dermatology. 2007 Aug;57(2):247-56.
4. Juhl, C et al. "Dairy Intake and Acne Vulgaris: a Systematic Review and Meta-Analysis of 78,529 Adolescents and Young Adults." Journal of Nutrients. 2018 Aug; 10(8): 1049.
5. Mahmood, S et al. "Diet and Acne Update: Carbohydrates emerge as the main culprit." Journal of Drugs and Dermatology. 2014 Apr;13(4):428-35.