Why you shouldn’t exercise to lose weight, explained with 60+ studies
“I’m going to make you work hard,” a blonde and perfectly muscled fitness instructor screamed at me in a recent spinning class, “so you can have that second drink at happy hour!”
At the end of the 45-minute workout, my body was dripping with sweat. I felt like I had worked really, really hard. And according to my bike, I had burned more than 700 calories. Surely I had earned an extra margarita.
The spinning instructor was echoing a message we’ve been getting for years: As long as you get on that bike or treadmill, you can keep indulging — and still lose weight. It’s been reinforced by fitness gurus, celebrities, food and beverage companies like PepsiCo and Coca-Cola, and even public-health officials, doctors, and the first lady of the United States. Countless gym memberships, fitness tracking devices, sports drinks, and workout videos have been sold on this promise.
There’s just one problem: This message is not only wrong, it’s leading us astray in our fight against obesity.
To find out why, I read through more than 60 studies on exercise and weight loss. I also spoke to nine leading exercise, nutrition, and obesity researchers. Here’s what I learned.
1) An evolutionary clue to how our bodies burn calories
When anthropologist Herman Pontzer set off from Hunter College in New York to Tanzania to study one of the few remaining hunter-gatherer tribes on the planet, he expected to find a group of calorie burning machines.
Unlike Westerners, whoincreasingly spend their waking hours glued to chairs, the Hadza are on the move most of the time. Men typically go off and hunt — chasing and killing animals, climbing trees in search of wild honey. Women forage for plants, dig up tubers, and comb bushes for berries. “They’re on the high end of physical activity for any population that’s been looked at ever,” Pontzer said.
By studying the Hadza’s lifestyle, Pontzer thought he would find evidence to back the conventional wisdom about why obesity has become such a big problem worldwide. Many have argued that one of the reasons we’ve collectively put on so much weight over the past 50 years is that we’re much less active than our ancestors.
Surely, Ponzer thought, the Hadza would be burning lots more calories on average than today’s typical Westerner; surely they’d show how sluggish our bodies have become.
On several trips in 2009 and 2010, he and his colleagues headed into the middle of the savanna, packing up a Land Rover with camping supplies, computers, solar panels, liquid nitrogen to freeze urine samples, and respirometry units to measure respiration.
In the dry, open terrain, they found study subjects among several Hadza families. For 11 days, they tracked the movements and energy burn of 13 men and 17 women ages 18 to 75, using a technique called doubly-labeled water — the best known way to measure the carbon dioxide we expel as we burn energy.
When they crunched the numbers, the results were astonishing.
“We were really surprised when the energy expenditure among the Hadza was no higher than it is for people in the US and Europe,” says Pontzer, who published the findings in 2012 in the journal PLoS One. While the hunter-gatherers were physically active and lean, they actually burned the same amount of calories every day as the average American or European, even after the researchers controlled for body size.
Pontzer’s study was preliminary and imperfect. It involved only 30 participants from one small community.
But it raised a tantalizing question: How could the hunting, foraging Hadza possibly burn the same amount of energy as indolent Westerners?
As Pontzer pondered his findings, he began to piece together an explanation.
First, scientists have shown that energy expenditure — or calories burned every day — includes not only movement, but all the energy needed to run the thousands of functions that keep us alive. (Researchers have long known this, but few had considered its significance in the context of the global obesity epidemic.)
Calorie burn also seems to be a trait humans have evolved over time that has little to do with lifestyle. Maybe, Pontzer thought, the Hadza were using the same amount of energy as Westerners because their bodies were conserving energy on other tasks.
Or maybe the Hadza were resting more when they weren’t hunter-gathering to make up for all their physical labor, which would also lower their overall energy expenditure.
This science is still evolving. But it has profound implications for how we think about how deeply hardwired energy expenditure is and the extent to which we can hack it with more exercise.
If the “calories out” variable can’t be controlled very well, what might account then for the difference in the Hadza’s weights?
“The Hadza are burning the same energy, but they’re not as obese [as Westerners],” Pontzer said. “They don’t overeat so they don’t become obese.”
This fundamental concept is part of a growing body of evidence that helps explain a phenomenon researchers have been documenting for years: that it’s extremely difficult for people to lose weight once they’ve gained it by simply exercising more.
2) Exercise is excellent for health
Before we dive into why exercise isn’t that helpful for slimming, let’s make one thing clear: No matter how working out impacts your waistline, it does your body and mind good.
A Cochrane Review of the best-available research found that, while exercise led to only modest weight loss, study participants who exercised more (even without changing their diets) saw a range of health benefits, including reducing their blood pressure and triglycerides in their blood. Exercise reduces the risk of Type 2 diabetes, stroke, and heart attack.
A number of other studies have also shown that people who exercise are at a lower risk of developing cognitive impairment from Alzheimer’s and dementia. They also score higher on cognitive ability tests — among many, many other benefits.
If you’ve lost weight, exercise can also help weight maintenance when it’s used along with watching calorie intake.
3) Exercise alone is almost useless for weight loss
So the benefits of exercise are real. And stories about people who have lost a tremendous amount of weight by hitting the treadmill abound. But the bulk of the evidence tells a less impressive story.
Consider this review of exercise intervention studies, published in 2001: It found that after 20 weeks, weight loss was less than expected, and that “the amount of exercise energy expenditure had no correlation with weight loss in these longer studies.”
To explore the effects of more exercise on weight, researchers have followed everybody from people training for marathons to sedentary young twins, and post-menopausaloverweight and obese women who ramp up their physical activity through running, cycling, or personal training sessions. Most people in these studies typically only lost a few pounds at best, even under highly controlled scenarios where their diets were kept constant.
Other meta-analyses, which looked at a bunch of exercise studies, have come to similarly lackluster conclusions about exercise for losing weight. This Cochrane Reviewof all the best-available evidence on exercise for weight loss found that physical activity alone led to only modest reductions. Ditto for another review published in 1999.
University of Alabama obesity researcher David Allison sums up the research this way: Adding physical activity has a very modest effect on weight loss — “a lesser effect than you’d mathematically predict,” he said.
We’ve long thought of weight loss in simple “calories in, calories out” terms. In a much-cited 1958 study, researcher Max Wishnofsky outlined a rule that many organizations — from the Mayo Clinic to Livestrong — still use to predict weight loss: A pound of human fat represents about 3,500 calories; therefore cutting 500 calories per day, through diet or physical activity, results in about a pound of weight loss per week. Similarly, adding 500 calories a day results in a weight gain of about the same.
Today, researchers view this rule as overly simple. They now think of human energy balance as “a dynamic and adaptable system,” as one study describes. When you alter one component — cutting the number of calories you eat in a day to lose weight, doing more exercise than usual — this sets off a cascade of changes in the body that affect how many calories you use up, and in turn, your body weight.
For weight loss, calorie restriction seems to work better than exercise, and calorie restriction plus exercise can work a little better than calorie restriction alone, according to Allison.
4) Exercise accounts for a small portion of daily calorie burn
One very underappreciated fact about exercise is that, even when you work out, those extra calories burned only account for a tiny part of your total energy expenditure.
“In reality,” said Alexxai Kravitz, a neuroscientist and obesity researcher at the National Institutes of Health, “it’s only around 10 to 30 percent [of total energy expenditure] depending on the person (and excluding professional athletes that workout as a job).”
Components of total energy expenditure for an average young adult woman and man.
There are three main components to energy expenditure, Kravitz explained: 1) basal metabolic rate, or the energy used for basic functioning when the body is at rest; 2) the energy used to break down food; and 3) the energy used in physical activity.
We have no control over our basal metabolic rate, but it’s our biggest energy hog. “It’s generally accepted that for most people, the basal metabolic rate accounts for 60 to 80 percent of total energy expenditure,” Kravitz said. Digesting food accounts for about 10 percent.
“It’s not nothing, but it’s not nearly equal to food intake — which accounts for 100 percent of the energy intake of the body,” Kravitz said. “This is why it’s not so surprising that exercise leads to [statistically] significant, but small, changes in weight.”
5) It’s hard to create a significant calorie deficit through exercise
Using the National Institutes of Health Body Weight Planner — which gives a more realistic estimation for weight loss than the old 3,500 calorie rule — mathematician and obesity researcher Kevin Hall created this model to show why adding a regular exercise program is unlikely to lead to significant weight loss.
National Institutes of Health Body Weight Planner.
If a hypothetical 200-pound man added 60 minutes of medium intensity running four days per week while keeping his calorie intake the same, and he did this for 30 days, he’d lose five pounds. “If this person decided to increase food intake or relax more to recover from the added exercise, then even less weight would be lost,” Hall added. (More on these “compensatory mechanisms” later.)
So if one is overweight or obese, and presumably trying to lose dozens of pounds, it would take an incredible amount of time, will, and effort to make a real impact through exercise.
6) Exercise can undermine weight loss in other, subtle ways
How much we move is connected to how much we eat. As Hall put it, “I don’t think anybody believes calories in and calories out are independent of each other.” And exercise, of course, has a way of making us hungry — so hungry that we might consume more calories than we just burned off.
One 2009 study shows that people seemed to increase their food intake after exercise — either because they thought they burned off a lot of calories or because they were hungrier. Another review of studies from 2012 found people generally overestimated how much energy exercise burned and ate more when they worked out.
“You work hard on that machine for an hour, and that work can be erased with five minutes of eating afterward”
“You work hard on that machine for an hour, and that work can be erased with five minutes of eating afterward,” Hall added. A single slice of pizza, for example, could undo the benefit of an hour’s workout. So could a cafe mocha or an ice cream cone.
There’s also evidence to suggest that some people simply slow down after a workout, using less energy on their non-gym activities. They might decide to lay down for a rest, fidget less because they’re tired, or take the elevator instead of the stairs.
These changes are usually called “compensatory behaviors” — and they simply refer to adjustments we may unconsciously make after working out to offset the calories burned.
7) Exercise may cause physiological changes that help us conserve energy
The most intriguing theories about why exercise isn’t great for weight loss describe changes in how our organs regulate energy after exercise.
Researchers have discovered a phenomenon called “metabolic compensation,”whereby, as people either expend more energy through physical activity or lose weight, their basal metabolic rate slows down.
“The more you stress your body, we think there are changes physiologically — compensatory mechanisms that change given the level of exercise you’re pushing yourself at,” said Loyola University exercise physiologist Lara Dugas. In other words, our bodies may actively fight our efforts to lose weight.
This effect has been well documented, though it may not be the same for everyone.
For one fascinating study, published in the journal Obesity Research in 1994, researchers subjected seven pairs of sedentary young identical twins to a 93-day period of intense exercise. For two hours a day, nearly every day, they’d hit a stationary bike.
The twins were also housed as in-patients in a research lab under 24-hour supervision and fed by watchful nutritionists who measured their every calorie to make sure their energy intake remained constant.
Despite going from being mostly sedentary to spending a couple of hours exercising almost every day, the participants only lost about 11 pounds on average, ranging from as little as 2 pounds to just over 17 pounds, almost all due to fat loss. The participants also burned 22 percent fewer calories through exercise than the researchers calculated prior to the study starting.
By way of explanation, the researchers wrote that either subjects’ basal metabolic rates slowed down or they were expending less energy outside of their two-hour daily exercise block.
Dugas called this phenomenon “part of a survival mechanism”: The body could be conserving energy after exercise to try to hang on to stored fat for future energy needs. Again, researchers don’t yet know why this happens, and how long the effects persist in people.
“We know with confidence that some metabolic adaptions occur under some circumstances,” said David Allison, “and we know with confidence some behavioral compensations occur under some circumstances. We don’t know how much compensation occurs, under which circumstances, and for whom.”
8) Energy expenditure might have an upper limit
Another hypothesis about why it’s hard to lose weight through exercise alone is that energy expenditure plateaus at a certain point. In another Pontzer paper, published in 2016 in the journal Current Biology, he and his colleagues found evidence of an upper limit.
They cast a wide geographic net, recruiting 332 adults from Ghana, South Africa, Seychelles, Jamaica, and the United States. Tracking the study participants for eight days, they gathered data on physical activity and energy burned using accelerometers. They classified people into three types: the sedentary folks, the moderately active (who exercised two or three times per week), and the super active (who exercised about every day). Importantly, these were people who were already doing a certain amount of activity, not people who were randomized to working out at various levels.
Here, physical activity accounted for only 7 to 9 percent of the variation in calories burned among the groups. Moderately active people burned more energy than people who were sedentary (about 200 calories more each day), but above that, the energy used up seemed to hit a wall.
“After adjusting for body size and composition,” the researchers concluded in the study, “total energy expenditure was positively correlated with physical activity, but the relationship was markedly stronger over the lower range of physical activity.”
In other words, after a certain amount of exercise, you don’t keep burning calories at the same rate: Total energy expenditure may eventually plateau.
In the traditional “additive” or “linear” model of total energy expenditure, how many calories one burns is a simple linear function of physical activity.
“That plateau is really different than the standard way of thinking about energy expenditure,” Pontzer said. “What the World Health Organization and the people who build the Fitbit would tell you is that the more active you are, the more calories you burn per day. Period, full stop.”
In the “constrained” model of total energy expenditure, the body adapts to increased physical activity by reducing energy spent on other physiological activities.
Based on the research, Pontzer has proposed a new model that upends the the old “calories in, calories out” approach to exercise, where the body burns more calories with more physical activity in a linear relationship (also known as the “additive” model of energy expenditure).
He calls this the “constrained model” of energy expenditure, which shows that the effect of more physical activity on the human body is not linear. In light of our evolutionary history — when food sources were less reliable — he argues that the body sets a limit on how much energy it is willing to expend, regardless of how active we are.
“The overarching idea,” Pontzer explained, “is that the body is trying to defend a particular energy expenditure level no matter how active you get.”
This is still just a hypothesis. He and others will need to gather more evidence to validate it, and reconcile contradictory evidence showing that people can burn more energy as they add physical activity. So for now, it’s a fascinating possibility, among all the others, that may help explain why joining a gym as a sole strategy to lose weight is often an exercise in futility.
9) The government and the food industry are doling out unscientific advice
Since 1980, the obesity prevalence has doubled worldwide with about 13 percent of the global population now registering as obese, according to the World Health Organization. In the United States, nearly 70 percent of the population is either overweight or obese.
A lack of exercise and too many calories have been depicted as equal causes of the crisis. But as researchers put it in an article in BMJ, “You cannot outrun a bad diet.”
Since at least the 1950s, Americans have been told that we can. This Public Health Reports paper outlines the dozens of government departments and organizations — from the American Heart Association to the US Department of Agriculture — whose campaigns suggested more physical activity (alone or in addition to diet) to reverse weight gain.
Unfortunately, we are losing the obesity battle because we are eating more than ever. But the exercise myth is still regularly deployed by the food and beverage industry — which are increasingly under fire for selling us too many unhealthy products.
“Physical activity is vital to the health and well-being of consumers,” Coca-Cola says. The company has been aligning itself with exercise since the 1920s, and was recently exposed by the New York Times for funding obesity researchers who emphasize a lack of physical activity as the cause of the the epidemic.
Physical activity and diet should never be given equal weight in the obesity debate
It’s just one of many food companies that’s encouraging us to get more exercise (and keep buying their products while while we’re at it): PepsiCo, Cargill, and Mondelez have all emphasized physical activity as a cause of obesity.
The exercise myth for weight loss also still appears in high-profile initiatives like the first lady’s Let’s Move! campaign — largely because of the food industry’s lobbying efforts, according to Marion Nestle, New York University nutrition professor. The White House’s exercise focus to end childhood obesity, Nestle said, was “a strategic decision to make the message positive and doable and, at the same time, keep the food industry off its back.”
But this focus on calories-out, or the calories we can potentially burn in exercise, is “an inadequate and a potentially dangerous approach, because it is liable to encourage people to ignore or underestimate the greater impact of energy-in,” an obesity doctor and professor wrote in the journal Public Health Nutrition.
In other words, we can lose sight of the fact that it’s mostly too much food that’s making us fat. “There are all kinds of reasons to exercise that are good for your health,” says Diana Thomas, a Montclair State University obesity researcher. “However, if you’re trying to lose weight, the biggest problem I see is food. We need to cut back the food we’re eating.”
The evidence is now clear: Exercise is excellent for health, but it’s not important for weight loss. The two things should never be given equal weight in the obesity debate.
10) So what actually works for weight loss?
At the individual level, some very good research on what works for weight loss comes from the National Weight Control Registry, a study that has parsed the traits, habits, and behaviors of adults who have lost at least 30 pounds and kept it off for a minimum of one year. They currently have more than 10,000 members enrolled in the study, and these folks respond to annual questionnaires about how they’ve managed to keep their weight down.
The researchers behind the study found that people who have had success losing weight share a few things in common: They weigh themselves at least once a week. Theyrestrict their calorie intake, stay away from high-fat foods, and watch their portion sizes. They also exercise regularly.
But note: These folks use physical activity in addition to calorie counting and other behavioral changes. Every reliable expert I’ve ever spoken to on weight loss says the most important thing a person can do is to limit calories in a way they like and can sustain, and focus on eating more healthfully.
In general, diet with exercise can work better than calorie cutting alone, but with onlymarginal additional weight-loss benefits. Consider this chart from a randomized trialthat was done on a group of overweight folks: The group that restricted calories lost about the same amount of weight as the group that dieted and exercised, though the exercisers didn’t cut as many calories:
The calorie restriction groups lost more weight than the group who both dieted and exercised.
If you embark on a weight-loss journey that involves both adding exercise and cutting calories, Montclair’s Diana Thomas warned not to count those calories burned in physical activity toward extra eating.
“Pretend you didn’t exercise at all,” she said. “You will most likely compensate anyway so think of exercising just for health improvement but not for weight loss.”
In this candid interview Dr. Pamela Popper, the author of FOOD OVER MEDICINE, answers some deep and through provoking questions:
1. Protein Supplements: Are vegan protein supplements dangerous? Should vegan athletes supplement?
2. Kidney Stones: Can vegans get kidney stones? What would cause a seemingly healthy individual to develop them?
3. Gluten: Is it as dangerous as we hear? Should healthy individuals avoid gluten products?
4. Medication: Learn if there are ever times you should medicate.
5. Supplements: Should a healthy individual take vitamins?
6. Are fortified foods a good idea?
7. Hormones: Are cruciferous vegetables really bad for us, or is it simply a myth to keep us from living healthy?
8. Should we supplement with iodine? Can iodine cause hypothyroidism?
9. Is salt allowed in a healthy diet?
10. How much and what kind of water should we drink?
11. Probiotics: Who should take them? In Food Over Medicine Dr. Popper suggests that people with certain health conditions, and those who had ever used birth control or antibiotics, should go through a prescription-strength probiotic treatment. I asked Dr. Popper if I, seven years into my health quest, with six of those off birth control, should still consider a probiotic treatment. Find out what suggested.
12. Health Insurance: How much of it do we really need?
13. Green Smoothies: Is there any truth to the rumors that they might not be good for us?
14. Does coconut oil have any healing properties?
15. Do you need to be vegan to be healthy?
18 Probiotic Foods for a Healthy Gut
By Olivia Tarantino
There’s a war going on inside your gut—and the good guys might be losing. It’s about time you called in reinforcements for your wounded front line and take back the good gut health that should be yours.
Years of antibiotic use (either by prescription drugs or by eating conventionally-raised meats), eating sugar-laden food, and eschewing microbe-feeding fibers are all making you fat—but not for the reason you think. This pattern of drug use and poor eating has also armed the bad bacteria who live in your gut with the weapons they need to overtake the good guys. And when your good gut bugs are depleted, they not only won’t be able to fend off weight-inducing inflammation, they also can’t help you keep your metabolism humming, your immune system healthy, and your mind keen.
That’s because research has shown that our gut microbes play a significant role in regulating our health and weight. And even more research has suggested a way we might mend this imbalance: by eating foods full of probiotics (and by also cutting out bad-microbe-feeding sugars and loading up on prebiotics.) You may have heard about probiotics before, but you’re about to turn the corner and see what they’re all about!
Probiotics are live bacterial cultures that we consume in fermented foods. They’re called “pro” because they’re believed to be beneficial to our health, although the science behind it has yet to prove how. (Or even if they are effective—as live probiotics often do not survive the harsh environment of the stomach—which is why the FDA has yet to approve using probiotic supplements to treat health problems.) A possible mechanism, described by a summary in the journal Gut, is that probiotics help rebalance your gut bugs by creating an environment where the good guys can regain strength.
Preliminary findings are promising. A study published in the British Journal of Nutrition found that overweight women who were put on a calorie-restricted diet and given a probiotic supplement for 12 weeks showed significantly higher weight loss than those given a placebo. Other studies have found probiotics can help alleviate IBS and IBD symptoms, eczema, infectious diarrhea, and may help prevent allergies and colds. The A-lister usually mentioned is yogurt, but probiotic sources go way beyond breakfast. Here are some of the best sources of natural probiotics you can consume to get your gut back in check—and to win the battle once and for all.
Dark chocolate is like getting a superhero and a sidekick in just one bar. That’s because it’s been found to be a source of prebiotics and probiotics. Prebiotics are a source of food for the microbes in your gut, which convert the candy into anti-inflammatory compounds, researchers at the American Chemical Society found. And probiotic bugs will colonize your belly to assist with digestion and strengthen your belly bugs so you can fix an off-kilter gut. The reason? Chocolate is actually a fermented food. Who knew? To reap the benefits, the ACS researchers recommend a cacao content of 70 percent or above, consuming about two tablespoons of cocoa powder or three-quarters of an ounce (usually a square) of a bar.
The most popular probiotic, yogurt is made by adding two strains of bacteria, Streptococcus thermophilus and Lactobacillus bulgaricus, into pasteurized milk. The milk thickens up from the lactic acid that’s produced by the bacteria, becoming the creamy product that you trust to build muscle. But while most Greek yogurts can be a trusted source of protein, not all will provide probiotics. Some products are heat-treated after fermentation, which typically kills most of the beneficial active cultures, so be sure to check the label for the phrase “live active cultures.” And be sure to stay away from the ones with added sugars which will do more for the bad bacteria than they will for the good.
Probiotics in peas? Japanese researchers say there are! A 2014 study published in the Journal of Applied Microbiology found that green peas contain Leuconostoc mesenteroides, a potent probiotic often associated with fermentation under low-temperature conditions. The bugs stimulate your immune system, helping to protect the mucosal barrier, a.k.a. the body’s second skin, which runs through your digestive tract and is the first line of defense against bad bugs and toxins. Pass on the canned stuff, but add fresh ones to pasta, salads, and omelets.
Don’t let its association with hot dogs sully your opinion of this food. Sauerkraut is lacto-fermented cabbage, and it contains natural compounds that have potent cancer-fighting and belly-slimming properties. When unpasteurized, sauerkraut is rich in Lactobacillus bacteria—even more so than yogurt—which boosts the healthy flora in the intestinal tract, bolsters your immune system, and even improves your overall health: Mice fed a probiotic-rich sauerkraut extract had reduced cholesterol levels, found a study published in World Journal of Microbiology and Biotechnology. Again, examine the label before you pick up a kraut for probiotic purposes. Store-bought, shelf-stable sauerkrauts can be pasteurized and prepared using vinegar, which does not offer the beneficial bacteria but mimics the same distinctive sour-taste which is traditionally produced by the fermented lactic acid. To get an authentic product, check out what the folks over at Farmhouse Culture are doing.
Kombucha is a slightly effervescent (aka it’s bubbly!) fermented drink made with black or green tea and a symbiotic culture of bacteria and yeast, known as a SCOBY. This functional food will only confirm its probiotic benefits if it isn’t pasteurized, which means the time between when it’s on the shelf and when it gets to your mouth increases the risk of contamination. In fact, unpasteurized kombucha drinks have been linked to bacterial infections, allergic reactions, and liver damage. So if you want to heal your gut, make your own at home and drink it within a couple days. As for the shelf versions? Only drink it if you like the taste—it likely won’t be benefiting your belly.
Kimchi is an Asian fermented veggie dish, made with cabbage, radishes, and scallions. That distinctive red color comes from a seasoned paste of red pepper, salted shrimp, or kelp powder. The unique strains found in kimchi won’t just heal your gut, they might also help you stay slim: Researchers at Kyung Hee University in Korea induced obesity in lab rats by feeding them a high-fat diet and then fed one group of them Lactobacillus brevis, the culture strain found in kimchi. The probiotic suppressed the diet-induced increase in weight gain by 28 percent!
These shouldn’t be your go-to source of probiotics, but fermented alcoholic beverages like beer and wine do actually provide some benefits when consumed in moderation. The vitamins from the barley grain that beer is made out of surviving the fermentation and filtering process and can lead to good cholesterol and decrease blood clot formation. And wine has been found to be a potent source of free-radical fighting antioxidants. To see how else drinking your glass of bubbly or red can be good for you, check out these 23 Surprising Healthy Benefits of Alcohol!
Double martini, please—and by double we mean the olive. Salt-water brined olives undergo a natural fermentation, and it’s the acids produced by the lactic acid bacteria which are naturally present on the olive which give these little fruits their distinctive flavor. Two strains of live cultures, Lactobacillus plantarum and Lactobacillus pentosus, have been isolated in olives, and L. plantarum shows great potential for getting you that flat stomach you’re after: This strain can balance your gut bugs and decrease bloating, particularly in people with irritable bowel syndrome, according to a study published in the American Society for Clinical Nutrition.
It might look funky, but natto is one of the healthiest foods for women—and here’s why: this Japanese dish of fermented soybeans is unique in that it’s the highest dietary source of vitamin K2, a vitamin which is important for cardiovascular and bone health as well as promoting skin elasticity to help prevent wrinkles. On top of that (and the reason it’s on this list) natto is a potent source of gut-healing probiotics. A healthy gut can keep inflammation at bay, which researchers say may affect the health of our skin since many troubles like acne, eczema, and psoriasis stem from inflammation.
Although this smoothie-like dairy drink resides next to yogurt, if you have a dairy-intolerance, this might be your better pick. That’s because kefir has been found to counteract the effects of the milk’s stomach-irritating lactose: Ohio State University researchers found that knocking back this fermented drink can reduce bloating and gas brought on by lactose consumption by 70 percent! What’s even more promising about kefir is that its bacteria have been found to colonize the intestinal tract, which makes them more likely to confer their healing benefits to your gut.
Pickles are another classic fermented veggie option. “But it’s important to distinguish that not all pickled vegetables are fermented,” say dieticians Willow Jarosh MS, RD, and Stephanie Clarke, MS, RD, co-owners of C&J Nutrition. “In order to get the health benefits from eating fermented foods, you’ll want to be sure that the pickled veggie you’re eating is, in fact, fermented—and not just pickled.” Shelf-stable products are the first sign a pickle is just pickled because the product would be pasteurized first, which kills off any bacteria—even the good ones. Make your own fermented pickles, and other veggies, at home with a starter, salt, and water.
We love miso, and you will too when you hear of its gut-friendly benefits! You’re probably familiar with it in the appetizer miso soup you get in restaurants, but you can also find this traditional Japanese paste in supermarkets. It’s made by fermenting soybeans with salt and koji—a fungus called Aspergillus oryzae. Not only is it a complete protein (meaning it contains all 9 essential amino acids) because it comes from soybeans, but miso also stimulates the digestive system, strengthens the immune system, and reduces the risk of multiple cancers.
Contrary to what you may think, sourdough is not a flavor; it’s actually the fermentation process where wild yeast and friendly bacteria break down the gluten and sugar in the wheat flour, turning it into good-for-you proteins, vitamins, and minerals. The “sour” aspect is the taste from the wild yeast which comes from the air around you, and will often vary based on your location. Because the starches from the grains are predigested by the bacteria, this bread is much easier to digest than other types of over-processed white breads.
The probiotic trend has uncovered products virtually unknown to American markets, which is why you’ve probably never heard of Kvass. This drink originated in Russia, traditionally made in a similar way to a yeast beer but with stale rye bread rather than barley. Beet Kvass, on the other hand, uses beets as the source of starch and whey to speed the lacto-fermentation process. The longer the beets are left to ferment, the more developed the flavor will be. Beets are already a great source of potassium and dietary fiber, so fermenting them amplifies their positive digestive properties even more.
Like yogurt, not all cottage cheeses will contain live and active cultures. But one of the products that do is from a company called Good Culture. Though dairy products are packed with slow-digesting, muscle-building protein and have been shown to enhance probiotic absorption, this option might not be your best bet; Many cottage cheeses are full of sodium, which can cause bloating and put you at risk of hypertension when eaten in excess.
You’ll often seen tempeh as the vegan alternative to bacon—and, believe us, it’s much better for your gut. Tempeh is a fermented soy product made with a yeast starter that has a meaty, tender bite with a neutral flavor; it’s an open canvas for all your favorite seasonings. Besides the belly benefits, a standard 3-ounce serving of tempeh boasts 16 grams of protein and 8 percent of the day’s recommended calcium.
Many cheeses are created by fermentation, but not all fermented cheeses contain probiotics. Aged, soft cheeses—such as cheddar, gouda, parmesan, and swiss—are typically the only type which will maintain the beneficial bacteria. These cheeses start with adding a lactic acid bacterial culture to milk, which will form lactic acid and cause the milk to form curds and whey. The longer the cheese ages, the more beneficial bacteria for your belly.