“I know I need to pay attention to what I’m eating, and I’ve been eating healthy for about six of seven years now,” says the 5’11″ model, who consumes about 1,120 calories a day.
“Katherine does an amazing job eating three meals and two snacks, fueling her metabolism,” nutritionist Haylie Pomroy tells PEOPLE. But with her workout schedule “she could add at least 600 more healthy calories.”
On a typical menu for Webb: a homemade smoothie for breakfast, a spinach salad with strawberries and almonds for lunch and grilled chicken fingers and sweet potato fries for dinner.
“It’s all about self-control,” Webb, 24, says in PEOPLE’s Most Talked About Bodies issue.
The Splash contestant gets even more regimented as she gears up for a pageant or, more recently, for her Sports Illustrated swimsuit issue debut.
“I cut out any type of bread product, and cake, cookies, bagels,” she says. “When I eat a lot of sugar, I tend to bloat more.”
There are days, however, when Webb allows for a few indulgences. After shoots, “I treat myself to an unhealthy meal sometimes,” she says. “I usually go for all-American buffalo wings and French fries.”
And she works off those guilty pleasure calories by hitting the gym at least three times a week.
“I’m a believer in cardio,” she says. “That tends to trim fat faster than anything for me. And maybe I’ll do free weights one day.”
But overall, “I try my hardest not to stress myself out,” she says. “If I find myself thinking too much about what I eat, then I go crazy.”
For more on Webb’s daily diet and the diets of three more celebs known for their bods, pick up this week’s issue of PEOPLE, on newsstands Friday