You already know that eating a varied diet, rich in colorful fruits and vegetables, is the key to optimal health, but when it comes to weight loss, science has proven a case for monotony.MORE: Bust Out of Your Fruit and Vegetable RutResearchers at the University of Buffalo and the University of Vermont found that when offered the same meal every day for a week (aka a “mono-lunch”), people consumed about 125 fewer calories on the fifth day than they did on day one. Interestingly, study subjects who switched up their meals consumed 45 calories more at the end of the week. “While it’s absolutely true that eating a variety of foods is the best way to meet all your nutritional needs, the mono-diet may be logical for people who get overwhelmed by food options and fall back on familiar, unhealthy choices,” says Bonnie Taub-Dix, R.D., author of “Read It Before You Eat It.” “As long as the mono-meal is balanced and healthy, and you like routine and structure, eating the same meal every day could work for you.”The key to sticking with it: getting creative. Sounds counterintuitive, but we’ll explain:Focus on quality. “If you’re going to eat one thing every single day, make sure it’s the highest quality,” says Layne Lieberman-Liebelson, R.D., author of the upcoming “Eat Like a European: Beyond the Mediterranean Diet.” For example, if you love fish, make sure you choose ones low in mercury, such as wild salmon and mackerel, or go for organic vegetables and legumes, such as sweet potatoes and lentils.MORE: Go Organic When It Comes to This Type of ProduceChoose a base food. Make one item of food your mainstay and mix and match the side dishes. “Let’s say your base mono-meal is salmon; one day eat it with steamed spinach, the next, with broccoli,” says Taub-Dix. “Likewise, you can chop it up into a salad or filet it with a side dish.” Even better: Experiment with different seasonings and cooking styles. “It’s like wearing a white shirt every day but mixing it up with accessories and colorful jackets,” she says.Categorize your meals. You can broaden the mono-meal by selecting a theme (vegetarian, salads, sandwiches) and incorporating it into your meal plan, suggests Patricia Bannan, R.D., author of “Eat Right When Time is Tight.” “For example, there are so many ways to eat a healthy sandwich on whole wheat bread—grilled chicken or sliced turkey or tuna—that you probably won’t get bored,” she says.Mix and match. Can’t decide which of your favorite foods gets the honor of the mono-meal? Rotate three of the same lunches throughout the week, suggests Taub-Dix. “You’ll still get the benefit of structure and repetition, but also flexibility if you have a company party or a night out with friends and don’t have access to that one meal,” she says.MORE: Have a Light Lunch, Weight LessEat a mini mono-meal. Maybe your workday is too unstructured to commit to the mono-meal. You can still reap the benefits of a routine eating plan with your afternoon snack. Examples: “A 6-ounce container of organic low-fat or fat-free plain or vanilla yogurt with an ounce of walnuts or dry-roasted almonds,” says Lieberman-Liebelson. “Or make your banana the mono and rotate the prep: Pair it with either 6 ounces of plain Greek yogurt, one tablespoon of natural almond or peanut butter, or put it in a smoothie with one cup of baby kale and a half cup of almond milk.”Make an exception for dinner. For most busy people, breakfast often consists of grabbing something on the go, and lunch can be scarfing down whatever’s most convenient. So if you’re going to choose one time of day to eat your mono-meal, make it either of those mealtimes. “The evening is a time to relax, talk to your family and enjoy home-cooked food,” says Bannan. “Plus, relaxing the rules at this time may also prevent you from wandering into the kitchen later because you’re bored.”Tweak your habits. One way to sustain the diet long-term is to make your habits, rather than actual meals, consistent, suggests Tanya Zuckerbot, R.D., author of “The Miracle Carb Diet.” “You can commit to, say, eating a piece of fruit or lean protein with each meal or making sure you get in lots of fiber in any given week,” she says. “That way, you’re still following a structured eating plan but giving yourself hundreds of choices.”COLUMN: Are You Getting the Right Kind of Gorgeous Greens?