In case we didn’t have enough evidence the ketogenic diet—also known as a high-fat diet—isn’t such a great choice, here is some more. An international study, which included our very own Otago University, has found that high-fat diets can reduce how much ‘helpful’ bacteria you have in your gut, which can make you more vulnerable to inflammation, diabetes or heart disease.In the first study of its kind, a team of researchers collected the gut bacteria of young adults who followed either a low, medium or high-fat diet for six months. They wanted to see if varying levels of dietary fat could change the type and amount of healthy gut bacteria in otherwise healthy people in China, where the diet is shifting from a traditional one low in fat and high in carbs to a more Westernised high-fat, low-carb style of eating.They found that those who followed the low-fat diet gained a boost of beneficial bacteria like butyrate, a key energy source for bowel cells that has anti-inflammatory goodness. But those who followed the high-fat diet lost some of this key bacteria, which meant they had higher inflammatory triggers. The researchers also warned that over time, these changes to the gut could develop into undesirable metabolic disorders like diabetes, heart disease and strokes.The study also found that after six months every participant in all three groups had lost weight, but those on the low-fat diet lost the most – hardly surprising. The researchers admitted the study had its limitations because it was not entirely clear whether the weight loss prompted the changes or vice versa. And a sampling of the gut bacteria only happened at the start and the end of the six months, whereas more frequent sampling would have given a more complete picture of microbial changes.But the researchers say they believe their findings show a clear need to curb fatty foods, and, more importantly, to ditch those extreme high-fat diets that are oh-so-trendy right now.