Variety is the spice of life – unless you’re trying to lose weight.

Just ask Eva Mendes, who disappointed millions of fans hungry for her fabulous figure by revealing that she eats the exact same thing twice a day.

“For lunch, I usually have salmon and rice or quinoa, and I try to include a salad. I’ll eat the same thing for dinner,” she recently told Shape. “I’m a creature of habit that way. I don’t get bored with food.”

Apparently, neither do other celebs who stay strong and slim. Misty Copeland reveals in her new book “Ballerina Body,” out this week, that she stays on her toes by falling back on the same dishes. Her “perfect day” includes a whole wheat bagel for breakfast, a spinach salad with pecans for lunch, and grilled salmon with roasted veggies for dinner. She also retraces her steps with go-to snacks like bananas, nuts and dried mangoes, pretty much every day.

And compared to Olympic swimmer Michael Phelps’ infamous 12,000 calorie-a-day carb-bombs before the 2008 Beijing Games, which included French toast, five-egg omelets and entire pizzas, NBA Lebron James’ pregame fuel feels flat.

“Before competition for me would be like a chicken breast and maybe a little pasta. And before the game I might have a protein shake and some fruit,” James told Business Insider. “But as far as pies or pizza and sandwiches and French fries — I can’t.”

But you also can’t deny that these boring habits have helped make these superstars our #bodygoals. And science actually backs this same dish, different day approach.

The CDC, the American Heart Association and the Mayo Clinic all recommend meal planning and cooking the same things over again to cut calories, save money and avoid falling back on fast food in a pinch.

“The reason these diets are effective – and they are effective – is that after eating the same thing over and over and over again, you get so bored that you’re just not eating as much,” celebrity dietitian Tanya Zuckerbrot, founder of The F-Factor Diet, explained to Moneyish. “Studies have shown that the more you have to choose from, the more you eat.”

In one study, moviegoers who were given M&Ms in 10 different colors ate 43% more of them than those offered the same number of M&Ms in just seven colors. And remember: the different colors of M&Ms taste exactly the same.

A similar test found adults offered six different colors of flavored jellybeans mixed together in the same bowl ate 69% more than when the colors were each placed in separate bowls.

That’s why people overeat at buffets. Or why you can’t resist trying one of every hors d’oeuvre at a cocktail party, whereas if the waitstaff kept coming out with chicken skewers, you’d probably stop eating after one or two. Variety makes us eat more.

But restricting yourself too much can drive you to binge once the diet is over.

Take the 400 calorie-a-day Master Cleanse fast that Beyonce reportedly followed for her “Dreamgirls” role in 2006, which saw the “Lemonade” singer sipping, well, just lemonade stirred with cayenne pepper and maple syrup. That’s just not sustainable. “At some point, Beyonce and Jay-Z go to Italy and want a bowl of pasta, and the weight comes right back on,” said Zuckerbrot. “So what’s the point of doing something temporarily if you want permanent results?”

She recommends falling into a healthy eating routine that keeps you on track without having to think about what to eat too much, yet still leaves some room to play.

“Eva Mendes eats eggs every day, but it doesn’t have to be scrambled eggs,” said Zuckerbrot. “You could do fried eggs, two hard-boiled eggs, an egg white omelet with all different vegetables.”

Or if Zuckerbrot’s clients eat Greek yogurt every day, they can experiment with different flavors.

“There are ways of creating repetition with it being less boring,” she said

And if your diet commitment is flagging, there’s nothing more exciting than hitting your weight goals.

“People ask me, ‘Are you bored?’ I guess so, sometimes,” Zuckerbrot said, “But I’m not bored being a size 2!”