Fiber may not be the sexiest nutrient of the bunch—healthy fats are currently claiming that title—but there’s no doubt it’s one of the hardest working. It lowers inflammation, it promotes healthy gut microbes, it reduces the risk of heart disease… it’s basically the overachieving Miranda Hobbs of your pantry.
And according to Tanya Zuckerbrot, MS, RD—bestselling author of The F-Factor Diet—there’s another reason why it should be at the head of the class (er, your pantry). A high-fiber diet—meaning at least 35 grams per day—is really good at kicking your metabolism into high gear. Like, even more effective than the calories-in, calories-out model.
“Most diets slow down your metabolism, and that’s why people end up plateauing,” explains Zuckerbrot, naming juice cleanses and other calorie-restrictive regimens as the main culprits. Why? Your body compensates for the calorie deficit by slowing down your metabolism so it can maximize each calorie. Fiber, on the other hand, is completely indigestible, says Bonnie Taub-Dix, RDN, creator of Better Than Dieting and author of Read It Before You Eat It: Taking You from Label to Table. “Since fiber is hard for the body to break down, it takes work, thereby burning calories.” This effect is called thermogenesis.
“Most diets slow down your metabolism, and that’s why people end up plateauing.”
Zuckerbrot references a 2017 study published by the American Journal of Clinical Nutrition in which participants were asked to substitute whole grains (which contain a ton of fiber) for refined grains during a 6-week period. By the end of the study, participants who consumed more than 40 grams of the nutrient had increased their metabolism by more than 92 calories a day.
While it’s important to note that researchers tracked this increased metabolic rate independently of body weight changes, Zuckerbrot explains that because weight loss will inevitably have some effect on your metabolism, the study indicates that a high-fiber diet actually counteracts that effect.
Sounds almost too good to be true, right? Well, there is one major caveat you need to keep in mind before piling your plate with whole-wheat pasta and bread. “You still need to keep portion sizes in mind and look at the overall profile of a food,” advises Taub-Dix. Here, she and Zuckerbrot lay out some basic rules for meeting your daily fiber quota in the healthiest way possible. (And yes, low-carb keto eaters, most of these tips will work for you, too.)
Read on for nutrition pros’ favorite ways to load up on fiber—and boost your metabolism at the same time.
1. Don’t skip breakfast
“Not only does eating breakfast jumpstart your metabolism for the day, but it’s the perfect opportunity to meet up to half your daily fiber needs before noon,” says Zuckerbrot. For a brekky that keeps you fueled until lunchtime, she suggests pairing protein with fiber. This can look like a high-fiber cereal with unsweetened almond milk, overnight oats with fiber-rich figs, or Greek yogurt topped off with all your favorite berries.
2. Become even *more* obsessed with chia seeds
In case you didn’t know, a tablespoon of chia seeds contains a whopping 6g of fiber, with the added benefit of protein and skin-enhancing omega 3s. And luckily, it’s super easy to reap the benefits of these mighty seeds in pretty much everything. Bake them into your banana bread, sprinkle them atop unicorn smoothie bowls, or add them to some decadent bonbons.
3. Eat the skin on fruits and veggies
Your meal-prep game is about to get a lot easier. (Win!) According to Zuckerbrot, you can skip the peeling portion of the cooking process and go straight for the chopping. “The skin of fruits and vegetables is often where a good portion of the nutrients live, as well as the fiber,” she says. Just make sure to give your cukes, potatoes, and pears a nice long scrub before chowing down. (Because, pesticides).
4. Put your spiralizer to good use
Okay, so maybe your spiralizer has been sitting in the back of your junk drawer for the past couple of months. (No judgement here.) This might make it spark a little more joy in your life: You can easily freeze zucchini, carrot, and parsnip noodles (AKA: zoodles, coodles, and poodles) for fiber-packed weeknight pasta replacements. “These vegetables provide a low-calorie base to be paired with protein, more vegetables, and sauce,” says Zuckerbrot. So long, spaghetti coma.
5. Learn to read nutrition labels
Next time you’re perusing the aisles at your local Whole Foods, take a minute to compare the fiber content in different pasta sauces, protein bars, and cereals. Why? “The best way to make sure you’re getting fiber into your diet is to look at labels when choosing snacks and products and aim for those that are higher in fiber,” says Zuckerbrot. (Banza chickpea pasta and Flackers are among the items she says to add to your cart, pronto.)
Just be sure to look at the rest of the ingredients too, says Taub-Dix: “A gigantic bran muffin could add lots of calories in sugar, fat, and sodium, so be sure to read labels carefully to see the company your fiber keeps.” (And it goes without saying, the more intimate the ingredient posse, the better.)