“It’s not what you do once in a while, it’s what you do day in and day out that makes the difference.” —Jenny Craig
Have you ever eaten the same thing every day for a week straight?
To most people — foodies and nutritionists, especially — the idea probably sounds boring at best and, at worst, unhealthy.
In fact, it directly contradicts the United State Department of Agriculture’s (USDA) dietary guidelines, which suggest people “include foods from all food groups: vegetables, fruits, whole grains, low-fat dairy products and lean protein foods.”
And research supports variety in healthy food groups, showing that eating a variety of nutrient-dense foods like fruits and vegetables is associated with numerous positive health outcomes, such as increased longevity and decreased chronic disease risks.
However, new research is beginning to show some counterintuitive benefits to limited, repetitive eating, such as controlling junk-food consumption, which scientists are hopeful can help people achieve their dietary goals.
Food variety is simply a tool: The key is knowing when and how to use it.
Limit Unhealthy Options
You’ve probably at some point in your life eaten something particularly delicious (think ice cream or pizza) and exclaimed, “I could eat this every day for the rest of my life!”
Nutrition researchers at the University of Tennessee tried to call that bluff, designing a 2012 study of more than 200 adults split into two groups who were both placed on similar caloric diets. Half of the adults were limited to eating only two items of junk food of their choosing for an 18-month period.
Sure, they’d be better off skipping junk food altogether, but compared with the control group, the limited-variety group consumed fewer calories from junk food overall, suggesting that their boredom with their two choices led to lower consumption.
Hollie Raynor, Ph.D., a nutrition professor at the University of Tennessee, led the study and says their results indicate, “that limiting variety of a particular food group decreases consumption of a food group — which could help people trying to reduce intake of certain foods.”
In a 2001 review of the existing research on dietary variety, researchers suggest “a reduction in dietary variety of highly palatable, energy-dense foods may be useful in the treatment and prevention of obesity.” However, Raynor cautions that so far, research hasn’t shown conclusively that limiting junk-food variety leads to weight loss, just less junk food eaten.
So limiting the variety of junk food may help you eat less of it, which is a good first step, but is there a way to use this knowledge to help us fill up on healthier, more nutritious foods?
The answer is yes, and it’s thanks in part to something called sensory-specific satiety, which is when there is a reduction in satisfaction and intake with the consumption of a certain type of food and then the return of appetite when there is exposure to a new food.
Using Variety to Your Advantage
There is research in both humans and animals that shows that the greater variety of foods you have within a meal or in your diet, the more you'll eat. A 2013 study of more than 1,000 adults found a positive association between the variety of snacks and risk of being overweight over the course of five to nine years.
Maya Vadiveloo, a nutrition research fellow at the Harvard School of Public Health, is studying using dietary variety in a positive way — to increase consumption of healthy foods such as fruits and vegetables.
“If I give you as many apples as you want, over time your intake (in the same meal or day after day) will decrease because your appetite for that flavor, that texture, that particular food goes down," says Vadiveloo. "But once I give you a new food — say an orange — it’s not that you’re so sated that you won’t continue to eat, you were just sated from that flavor."
Increased consumption of fruits, vegetables, whole grains and legumes are associated with a variety of health benefits, including decreased chronic disease risk and decreased body weight, and Vadiveloo thinks dietary interventions could take advantage of these findings about variety to increase consumption of those food groups through novelty. Vadiveloo says she’s also working on a study to try to determine if novel ways of preparing a food can “trick” the brain out of the boredom that develops over repeated presentations of the same food.
“I’m interested in this line of research because it might help make a healthy diet pattern a little bit more enjoyable and tasty.”
When to Use Food Variety
How can you implement diet variety (or the lack thereof) to help improve your overall eating habits? Here are some simple steps:
Eat a wide variety of fruits and vegetables. Whole plant foods are both dense in micronutrients as well as relatively low in calories, so you can afford to eat larger amounts from this food group. Keep a variety of fruits and vegetables on hand at home. If you’re having a salad, try to include different types of healthy toppings with different flavors (beets, dried fruit, nuts, etc.)
Limit yourself to one kind of “treat.” While you’re obviously better off skipping junk food altogether, studies show that repressing your desires can lead to binge eating. Avoid getting variety packs of any high-calorie junk foods, such as full-fat ice cream, pastries and candy. Just pick one “treat” food and limit your intake.
Tackle buffets and barbecues with a game plan. When there’s a smorgasbord of different foods (and flavors) there’s a greater chance you’ll overeat. To avoid this, fill half your plate with healthy veggies and fruit salad, but limit the different types of unhealthier options like desserts and creamy side salads or dips.
Expand your palate. You might have your go-to vegetables or fruits for a meal or snacks, but change it up a bit. Each week, purchase a new fruit or vegetable that you’ve never eaten or cooked with before. Avoid repeating the same fruits or veggies each week to keep it interesting and hopefully increase the chances of you filling up on these lower-calorie foods.
Limit variety within a meal. Keeping meals simple (like a one-pot vegetable stew) will limit the variety of tastes you experience, and since increased variety can delay your feeling of fullness, simple meals may help you control how much you eat in a sitting.
Focus on the positive. While limiting the variety of junk foods and increasing the variety of healthy foods have both been shown to have positive effects, increasing variety of healthy foods appears to have more far-reaching impacts on long-term health and the research is more well-established.