Statistics on sugar consumption make for shocking reading. Until as recently as 300 years ago, humans only consumed a few pounds of sugar per year. Recent estimates show, the average person in the US consumes between 77 and 152 pounds of sugar a year, which equates to 100 g to 200 g a day.

Adolescents consume even more. In a study of 1000 American teenagers (aged 14 to 18), the average daily intake of added sugars for boys was 389 g and 276 g for girls. This means, many teenagers got up to 52% of their total calories from added sugar – and they wonder why acne is at epidemic levels.

Sugar is perhaps the worst food when it comes to acne, and more so for people prone to hormonal-type acne. While there are no studies specifically on sugar and acne, quite a few have have shown reducing dietary glycemic index (GI) improves acne. Sugar has a high GI, and reducing the GI of diet also means eating less sugar.

As we discussed in the what causes acne chapter, carbohydrates trigger insulin release from the pancreas, which both stimulates skin cell growth and triggers the release of acne-causing hormones.

Sugar comes primarily in 3 forms: glucose, fructose, and sucrose. Glucose is the same form as found in the bloodstream. Fructose is usually known as fruit sugar. Table sugar is sucrose, which is a combination of fructose and glucose.

Out of these, fructose seems to be most damaging.

In a 2014 study, researchers gave healthy adults three drinks (at separate times). One contained 50g of fructose, another 50g of glucose, and third one 50g of sucrose. Only the fructose drink increased systemic inflammation levels. For reference, a 12-oz (330ml) can of Coke contains 33g of sugar.

A 2010 study shows the shocking effect of high doses of fructose. In the study, the researchers gave 74 healthy adult men 200g of fructose a day. In only two weeks, 33% of these previously healthy men developed metabolic syndrome (MetS). MetS is a precursor state to diabetes and heart disease. People with MetS are insulin resistant and have higher than normal blood pressure and triglyceride levels – among other problems. The participants also showed signs of liver damage.

Granted, 200g of fructose is a lot. However, it’s not unrealistic. Many Americans consume 100g of fructose a day. If 200g a day was enough to cause serious damage in only two weeks, one can only imagine what 100g a day for months on end does to the body.

This was demonstrated in a study published in the American Journal of Clinical Nutrition in 2011. Young Swiss men were given beverages sweetened with 40g or 80g of fructose, sucrose, or glucose. After three weeks of consuming the sweetened beverages every day, the researchers noted 82% to 109% increase in inflammation levels. The drinks with the higher sugar content caused a larger increase in inflammation levels.

Sugar is especially harmful to people with too high androgen levels. High androgen levels change the immune system response to glucose. In women with normal androgen levels, glucose doesn’t cause a significant increase in inflammation. But in women with high androgen levels, ingestion of glucose triggers a big increase in inflammation levels.