Watermelon is very trendy right now. This juicy pink treat has been touted as helping reduce skin damage and redness caused from sun exposure, preventing future wrinkling and possibly even lower skin cancer risk. Wow. But what about for acne? All acne is hormonal to some extent, and our 'acne-causing' hormones (Insulin and IGF-1) are triggered by sugar intake. So shouldn't all the sugar in that sweet melon spike our insulin levels and trigger acne?
The answer is no.
Watermelon typically has a glycemic index of 72 ( which is quite high sugar, GI runs from 1 to 100) but it has a glycemic load of only 2 per 100 gram serving (GL gives a more real-world value of how a specific food can affect blood sugar levels, Watermelon has a low GL). This means that, despite it's high GI, eating Watermelon is unlikely to cause a spike in blood sugar and acne-causing insulin levels when eaten in 'normal' amounts.
But what about the anti-acne properties I've read about? Watermelon contains moderate amounts of lycopene. This is the pigment that gives the fruit its colour. It’s also a powerful antioxidant and there is some evidence that Lycopene is anti androgen and has been linked to decreasing IGF-1 which could make Watermelon 'anti-acne'. A lot of bloggers and marketeers have focused on this but there's no specific acne-lycopene research to back it up yet.
Also, the amount of Lycopene in Watermelon is still relatively small (a cup and a half of watermelon contains about 9 to 13 milligrams of lycopene) so you'd need to eat A LOT of Watermelon to get any real anti-acne benefit - which would then spike your insulin levels and lead to more acne.