Hailey Bieber in Bathing Suit Gets a "Happy Birthday" Wish

Happy birthday Hailey Bieber! Hailey turned 26 on November 22, and she's celebrating by sharing throwback photos with friends. The model reposted a photo of herself wearing a two-piece swimsuit, posing on a boat with Justin Bieber's stepmother Chelsey Bieber. How does she stay so fit? Read on to see 5 ways Bieber stays in shape and the photos that prove they work—and to get beach-ready yourself, don't miss these essential 30 Best-Ever Celebrity Bathing Suit Photos!

Hailey is very honest about having to be mindful of her diet to maintain her skin health and overall fitness. "On a regular day, breakfast is usually eggs or oatmeal, some type of healthy protein, or a smoothie," she says. "Lunch is usually salad, fish, grilled veggies, or maybe a sandwich. I don't really eat a lot of gluten so I'm trying to be particular. I love a good kale Caesar salad [but with] no croutons. That's usually one thing I leave out."

Hailey sometimes switches to a pescatarian diet, saying it gives her energy. "Eating fish is associated with many known health benefits," says Sydney Lappe, MS, RDN. "Despite this, most Americans fail to eat the recommended weekly amount of fish. On one hand, the benefits of eating fish include being a source of lean protein, bone-building nutrients, and heart-healthy fats. On the other hand, some people may be intimidated to cook with fish or may not be confident about the healthiest fish options with the lowest mercury risk."

Hailey understands that cheat days are sometimes necessary to stay healthy overall. "A cheat day for me, the first thing that I crave, I'll eat," she says. "That's my rule. So if I wake up and I want pancakes, I'm gonna eat pancakes. If I want a cheeseburger for lunch or for dinner, I'm gonna eat it. If I want fries, I'm gonna eat the fries."

Hailey loves to bake, but she's mindful of sugar for the sake of her health. "Cutting added sugars can help to keep your blood glucose levels within healthy parameters and makes it easier to control weight, both of which lower your diabetes risk," says Linda Folken, MS, RDN, CSOWM, CDN. "Added sugars contribute to excess calories, and excess calorie intake leads to weight gain. Weight gain, along with higher blood glucose levels from consuming added sugars, leads to insulin resistance. Cutting down on added sugars is key in stopping this cycle."

Hailey drinks plenty of water throughout the day, saying it's important for how she feels. "Every day, you lose eight to 12 cups of water through breathing, perspiring, and urine and bowel movements. In general, men need at least 12 cups of fluid daily, while women require a minimum of nine cups," says Allyn Wergin RDN. "Factors that increase your fluid needs include exercise, hot weather, high altitude, a high-fiber diet, and increased losses from caffeine and alcohol intake."