As the start of a new cycling season approaches, some of us might want to get leaner after several months of hibernating over the winter. If that’s a goal, it may make us more susceptible to the detoxifying and “fat burning” claims made about juice cleanses.
It’s easy to understand why—who wouldn’t want to get lean quickly and by doing nothing other than drinking juice? Making it even more tempting is the fact that juice cleanses remain a common fixture in the fitness scene.
There are “experts” a-plenty who promote the supposed health benefits of consuming nothing but juice for anywhere from 12 hours to several days. And the claimed benefits are many, ranging from “flushing” out your insides to burning fat to unlocking new levels of performance. Detoxing using juice cleansing is often marketed to athletes like cyclists as a way to increase fitness and get leaner, faster.
Above all, proponents of juice cleanses claim that they’re healthy and good for you.
Turns out, in reality that is not actually the case. Despite the myriad of marketing claims floating around about juice cleanses detoxifying our bodies, eliminating toxins, or “flushing fat,” there is zero scientific evidence to back up any of these assertions.
On the contrary, a new study found that juice cleanses can actually be detrimental to our health. A 2025 study published in Nutrients concluded that juice cleansing for even a short time can alter our gut microbiome in ways that are not to our benefit. Scientists found negative changes after subjects participated in juice cleansing for just 3 days.
The undesirable changes researchers discovered in the gut microbiome of study participants included an increased number of organisms associated with increased inflammation in the body, gut permeability, and cognitive decline. As Bicycling has previously reported, chronic inflammation can impede our performance, muscle recovery, and have insidiously harmful effects on our overall health long term.
As a rule of thumb, it’s wise and advisable to be skeptical of any method, supplement, or cleanse that promises quick-fix, fast results, even if these promises are made by influencers or “experts.” As the adage goes, if it’s too good to be true, it probably is.
The truth is that the most beneficial way to increase cycling performance and ride at our best is to give our body the ingredients it needs to feel its best. And the healthiest way to do that is by hydrating and fueling properly with a balanced diet of actual food.
This may seem boring compared to a flashy, colorful juice cleanse that looks great in a social media post, but in the case of detoxing and juice cleanses, appearances have been proven to be deceiving.
If you are struggling with an eating disorder and are in need of support, please call the National Eating Disorders Association Helpline at 1-800-931-2237. For a 24-hour crisis line, text “NEDA” to 741741.
Natascha Grief is Bicycling’s Health & Fitness Editor. She started in the cycling industry as a bike mechanic a couple of decades ago, earning a couple pro-mechanic certifications and her USA Cycling Race Mechanic license. She went on to apprentice for framebuilder Brent Steelman in her hometown of Redwood City, California before spending several years working for both large and not-so-large cycling brands. She then switched gears and industries to earn multiple personal training certifications while honing her skills as a trainer and coach, specializing in functional training, corrective exercise, and body positive personal training. She began contributing regularly to Runner’s World and Bicycling as a freelance writer in 2020, and joined the editorial staff of Bicycling in 2022.
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