Want a Happy Gut? Avoid This Bad Habit.

Do you eat healthfully during the week, but view weekends as a junk food free-for-all?

If so, you might be damaging the health of the trillions of precious microorganisms that reside in your gut, according to a new study.

This is vital information because those microorganisms are crucial to the health of your body and mind.


While the actual number of microbial cells that inhabit your gut is not known, it is believed that up to 100 trillion reside there. Those microorganisms play a vital role in the body: they influence metabolism, nutrition, and immune function. Gut microbiota disruptions have been linked with inflammation, gastrointestinal conditions, obesity, Type 2 diabetes, autoimmune disorders, liver disease, heart disease, attention deficit hyperactivity disorder, autism, Alzheimer’s disease, and cancer.

As you can see, the proper care and feeding of those gut critters is essential, so the findings of this new study are, well, pretty darn important, so keep reading.


Researchers at University of New South Wales found that yo-yoing between eating well during the week and binging on junk food over the weekend is likely to be just as bad for your gut health as a consistent diet of junk.

The research, led by Professor Margaret Morris, the Head of Pharmacology at UNSW, examined the impact of yo-yo dieting on the gut microbiota of rats. The findings have been published in the journal Molecular Nutrition and Food Research.

Professor Morris said the study was the first to compare how continuous or irregular exposure to an unhealthy diet can impact the composition of the gut microbiota.

The findings indicate that intermittent exposure to junk food three days a week is sufficient to extensively shift the gut microbiota towards the pattern seen in obese rats consuming the diet continuously.

A reduction in the diversity of the gut’s microbiota and a loss of some of the beneficial biota is clearly not a good thing for health.

While these findings are yet to be replicated in humans, those who are strict with their diet during the week may be undoing all their good work by hitting the junk food over the weekend.

The research team compared the abundance of microbiota in rats given continuous access to either a healthy diet or junk food with a group cycled between the two diets, healthy for four days and junk for three, over 16 weeks.

A range of metabolic markers, including body weight, fat mass, insulin and leptin, were also examined. At the end of the 16 weeks, rats on the cycled diet were 18% heavier than those on the healthy diet, while leptin and insulin levels in cycled rats were in between rats fed junk or healthy food.

But the gut microbiota of the cycled rats was almost indistinguishable from rats fed a constant diet of junk, with both groups’ microbiota significantly different from those in the rats fed a healthy diet. And, the junk food diet reduced the abundance of microbial species capable of metabolizing flavonoids, which are believed to not only assist in weight loss but also exert neuroprotective functions within the brain.

Cycled rats also showed large swings in food intake, consuming 30% more calories than those maintained on the healthy diet only. When cycled rats switched back to a healthy diet, they consumed half as much food as those maintained on a healthy diet only.

Of course, this study was in rats and additional research is needed, but if the same phenomenon occurs in humans, the implications are significant.

Professor Morris said a greater understanding of the role of calorie rich foods and dieting on microbial changes is important, especially considering the current obesity epidemic and the prevalence of yo-yo dieting in Western countries:

The study suggests certain gut microbiota, including Ruminococcus and Blautia, may be promising targets for future therapeutic strategies to treat metabolic disorders.


Even if your weekends have been binge-ful for quite some time , don’t despair: it isn’t too late to change your over-consuming ways and avoid permanent damage. Your gut biota profile can change relatively quickly, so you can introduce healthy lifestyle measures and improve your intestinal health. Experts recommend eating a healthy diet of unprocessed foods, including adequate fiber, avoiding excess alcohol, and getting enough exercise.

For in-depth information on dietary and lifestyle changes that can help reduce inflammation and improve gut health, please check out Depression Cause May Be Physical, Not Mental.

As for Professor Morris and her team, the next phase of their obesity and diet-related research will look at the links between the brain, behavior, and the gut’s microbiota.

Additional Resources

The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-term Health

Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain –for Life