The keto diet may not be the healthiest way to lose weight after all.  

By Lauren Wicks
Updated February 26, 2019
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Low-carb, high-fat diets (such as the keto diet) may be all the range right now, but more studies continue to show the negative long-term effects that can fester after you lose the weight. While fat is an extremely important component of our diets, and we should seek to enjoy heart-healthy options each day, a new study shows too much fat could seriously disrupt your microbiome.

Researchers from Harvard, Australia, New Zealand, and China studied the effects of dietary fat intake in healthy young adults and how differing amounts affected their microbiomes and cardiovascular health. Their findings, published in the journal, Gut, showed those who followed a high-fat diet experienced unfavorable changes in gut bacteria, leading to long-term gastrointestinal issues and an increased risk for metabolic diseases, such as Type 2 diabetes.

The researchers took 217 healthy adults between the ages of 18 and 35, and split them up into three groups with varying fat and carbohydrate intakes. Those on the low-fat diet consumed 20 percent of their daily calories from fat and 66 percent from carbs, while the high-fat dieters consumed 40 percent of their calories from fat and 46 percent from carbohydrates. The moderate-fat group ate a diet consisting of 30 percent fat and 56 percent carbohydrates. Every participant ate the same amount of protein and fiber. Participants were also required to give blood and stool samples at the beginning and end of the study.

Results showed those on the low-fat diet plan had higher levels of Blautia and Faecalibacterium, good bacteria that produce butyrate, a fatty acid with anti-inflammatory properties that’s known for positively influencing bowel movement. The low-fat diet group also saw a decrease in bacteria associated with metabolic disorders. The high-fat diet group saw a reverse effect, with a decrease in the anti-inflammatory bacteria and an increase in long-chain fatty acids, known for being inflammatory and linked to metabolic disorders.

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All three diet groups lost weight throughout the month, but the low-fat diet group lost the most on average. The authors of this study noted it is still unclear as to whether weight loss in this study was associated with metabolic markers, or changes in gut bacteria.

The bottom line: Both fat and carbs are essential nutrients to keep our bodies healthy and strong, but it is possible to have too much of a good thing. While some high-fat diets do provide amazing weight loss results, it is important to abide by a less restrictive, balanced lifestyle with more attainable goals and realistic principles.