Feeding the bacteria in your belly may be the key to dropping pounds.

Portrait of Tammy Strobel

Feeding the bacteria in your belly may be the key to dropping pounds.

My Reading Room

Liz Krieger investigates

Small can be very powerful—looking at you, split atom, microchip and mosquito—and that definitely holds true when it comes to bacteria in your gut. The 100 trillion tiny microbes, a.k.a. gut flora, that call your digestive tract home play a pivotal role in everything from your immune system to your digestion to your mood. But researchers are now convinced that there’s something else your microbiome (your internal microbial ecosystem) affects—your weight.

“The gut is connected to everything,” says Mark Hyman, M.D., Director of the Cleveland Clinic’s Center for Functional Medicine. “If your microbiome is out of whack, i.e., it doesn’t have enough good bacteria or too much bad bacteria, it can affect how your food is metabolised as well as lead to inflammation.” It’s a cascade of casualties: Bad bacteria in the gut can trigger inflammation—in your skin, joints, brain, everywhere— and send your body’s immune response into overdrive as it tries to rid the body of the bacteria. This can lead to insulin resistance, which can promote weight gain, says Hyman. The theory is that more good bacteria helps you process food more efficiently and reduces cravings. We are actually all born with very little bacteria in our guts, but through exposure that amount slowly increases. It varies wildly based on the type of birth (vaginal versus C-section), environment (city versus country), and diet and lifestyle factors. The average person today has a lot less bacteria than in the past, mostly because of a modern-day diet that’s low in probiotics (live microorganisms, including bacteria) and prebiotics, the fibres that feed probiotics, says Josh Axe, a clinical nutritionist and the author of Eat Dirt. Top it all off with antibiotic and hand-sanitiser overuse, both of which wipe out vital gut flora, and you have an imbalanced gut that could be causing you to hold on to extra pounds.

If it all sounds rather dire, consider this happy fact: Changes that you make today can very quickly—within a few days— begin to overhaul your microbiome profile, improve your overall gut health, and help efforts to lose weight. Here’s your action plan.


Avoid processed foods and items high in sugar and carbohydrates, says Axe. Studies have shown that both sugar and artificial sweeteners can decrease good bacteria levels in the gut.


Fibre can lower blood sugar, reduce cholesterol and promote weight loss, says Hyman. What’s more, fibre slows the rate at which food enters your blood stream and increases the speed at which it exits your body through the digestive tract, keeping you fuller longer. While all fibre is good, here are some great prebiotic fibre sources: Jerusalem artichokes, onions, garlic and leeks, as well as chia seeds, flax seeds and hemp seeds. Aim for 25g a day, if not more. Or consider a fibre supplement, says Hyman.

Try: GNC’s Natural Brand Super Fibre, which contains 6g of fibre per serving.


In one study, women who took probiotics for 24 weeks lost 51 percent more weight than those who didn’t. Yoghurt and kefir products contain live, active cultures, as do fermented foods like kimchi, miso and sauerkraut. It’s also a smart bet to take a probiotic supplement twice daily, says Hyman. “Look for at least 25 billion live CFUs [colony-forming units] from diversified strains of bacteria,” such as lactobacillus and Bifidobacterium, he adds.


There’s a complex interplay between your hormones and gut, and how they affect one another, notes Raphael Kellman, M.D., an integrative and functional medicine physician and the author of The Microbiome Diet. Low thyroid function, in particular, can contribute to gut sluggishness.


Nurturing the beneficial creatures in your digestive tract may be the surest route to reaching your healthiest weight. “Within a week of following a gut-friendly diet, you will notice a drop in cravings,” promises Kellman.

“And you could be eating the same amount of calories as you were before, but you will lose weight. In fact, you may be able to eat even more.