Is this new research another strong case against the cheat days gone overboard?
A new study from the University of New South Wales warned that yo-yoing between weekend binges and healthy eating on weekdays is likely just as damaging for gut health as a consistently bad diet.
The study – led by UNSW professor Margaret Morris and published in the journal Molecular Nutrition and Food Research – examined yo-yo dieting’s impact on the gut microflora of rat models. It claims to be the first to demonstrate how intermittent or continual exposure to unhealthy diets can affect gut microbiota.
The human stomach harbors up to 100 trillion good bacteria that affect nutrition, metabolism, and immunity. Disrupting this gut flora has been associated not only with gastrointestinal issues such as inflammatory bowel disease, but also bigger conditions such as obesity.
Morris said that the diversity of this gut microbiota and losing the good bacteria are bad news for one’s health.
“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,” she explained.
After 16 weeks, the team compared the abundance of gut microbiota in rats consuming a consistently healthy diet and those eating junk food, with another group cycled between the two dietary groups (healthy for four days, junk food for three). They investigated metabolic markers that include weight, fat mass, leptin, and insulin.
Rats on the cycled diet emerged as 18 percent heavier than those on the healthy diet. Their leptin and insulin levels, too, were in between those of the healthy and junk food rat groups.
Their microbiota were nearly no different from those of junk-food rats – both significantly reduced compared to the healthy-food rats. They exhibited large food intake swings, consuming 30 percent more energy than the healthy-food rats.
The junk-food rats, on the other hand, reduce their microbial species that can metabolize flavonoids, which are believed to help in weight loss and protect the brain.
“[T]he richness of the population is reduced, there's less different types of bacteria and there's a loss of some bacteria that may be beneficial to the gut, such as lactobacillus for instance,” said Morris in an interview, underscoring the importance of these gut organisms – a vibrant community outnumbering the cells in the body.
The findings are yet to be replicated in human subjects.
“[But] 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,” warned Morris, zeroing in on certain gut bacteria such as Ruminococcus and Blautia as potential targets for future metabolic therapies.
Pithawat Vachiramon | Flickr
