Hilary Swank credits her slender fitness to simple, good genes.
"I think I've been blessed with my father's metabolism," the double Oscar winner, 33, told PEOPLE as she arrived at a dinner in London Thursday.
Swank, in an ultra figure hugging black Dolce & Gabbana dress, co-hosted the dinner with perfume maker Guerlain at the yet-to-open Almada restaurant in Mayfair. She was celebrating her role as spokesperson and face of the beauty brand's latest ad campaign (just launched in London), for Insolence.
Swank, who famously bulked up for 2004's Million Dollar Baby
– and was named Best Actress in the process (her other Academy Award was for 1999's Boys Don't Cry
) – said despite good genetics, she still enjoys the rewards of working out.
"I really appreciate exercise because I think it's a great stress relief," she says. "I do this thing called power Pilates, which I love. love, love."
But ultimately it's Dad who gets the credit. "I try and get out as much as I can," she says, "but I think in the end I really have to give it up to my genes."
Greeting guests such as Kid Rock, Harry Connick Jr., Christian Slater, Bryan Ferry and Mick Jagger – who sat on one side of her during the meal, as her boyfriend, CAA agent John Campisi, sat on the other – Swank spoke to many of the 100 guests before enjoying a dinner of sea bass followed by chocolate torte.
After the dinner, Swank and John Campisi – the two have been dating since last year
– were spotted arm in arm. "They were glued to each other, hugging, arms wrapped around each other. She looked very, very happy," says one guest. "And so did he."
Who's turning 40? Which celebs are high school dropouts? What's hot and definitely not in fall fashion?
Check out PEOPLE's new digital magazine now!