Hayden Panettiere drinks water to stay in shape.

The 'Heroes' actress has revealed she speeds up her metabolism by drinking a glass of water before every meal.

She said: "I try to watch what I eat and I use a couple of tricks I have learned.

"Before every meal, I drink a glass of water and wait 10 minutes. This is supposed to start your metabolism, so when you eat, your metabolism is already going."

Hayden takes her time when she is having her meals to ensure she doesn't overeat and avoids dining too late in the evening.

The 19-year-old beauty added to Britain's Celebs on Sunday magazine: "I try to eat slowly because you don't realise how full your body is until 20 minutes later.

"I generally have breakfast as my biggest meal of the day, and I don't eat past a certain hour, although I am not always strict with these rules."

Hayden also swears by having regular facials and exercises on the treadmill in her living room when she is at home.