'Story Of My Life' superstars One Direction are currently on tour and revealed that making sure they eat healthily can be a struggle because all of them except for Niall Horan have to be careful with foods they consume if they're not able to work out. 

During a new interview with the May/June issue of Bop magazine, the lads opened up about who eats the most and member Zayn Malik admitted that it's definitely Irish heartthrob Niall Horan, and he's especially envious of that fact because Horan never gains weight:

"Funnily enough, it's Niall who's the skinniest member of our bunch. He just eats and eats and eats and eats, but doesn't actually put any weight on. It is a little bit annoying because the rest of us have to watch out with what we eat, but Niall can just eat anything and be fine."

Horan then gave his opinion on Malik's response, adding: "There's nothing wrong with eating all the time. Sleep 'til you're hungry, eat 'til you sleep!"

Watch footage from the lads' South American leg of their Where We Are tour below: