The lack of success in maintaining weight loss has usually been attributed to not following the diet that enabled the initial weight loss — but that simplistic idea doesn’t really take into account the fact that we’re all different, and our bodies can react differently to diets. Now, researchers are finding that blanket approaches may not be all that effective and instead, personalized diets may be the way to go.

A group of researchers from Stanford University found the bacteria living in your gut and the amount of certain proteins your body makes can affect your ability to maintain weight loss. And while some people in the study lost more pounds on low-fat diets, others did better on low-carb diets, which hints at the need for personalized diets.

The researchers have identified several biomarkers (a range of measures that capture what’s happening in a cell or organism) that predict how successful an individual will be at losing weight and maintaining it in the long term. These include levels of exhaled CO2, signatures from the gut microbiome, and proteins made by the human body.

“Weight loss is enigmatic and complicated, but we can predict from the outset with microbiome and metabolic biomarkers who will lose the most weight and who will keep it off,” Michael Snyder, professor and chair of genetics at the Stanford School of Medicine and co-senior author of the paper on weight loss, said in a media statement.

A very big problem

Obesity is a common, serious, and costly disease, as defined by the Centers for Disease Control and Prevention (CDC). Recent numbers report a 42.4% obesity prevalence in the US, increasing over the years. Obesity can lead to heart disease, stroke, and premature death and has an estimated annual medical cost of $173 billion in the US.

The new study shows that reducing calorie consumption or doing exercise wasn’t enough to maintain weight loss over a year. That’s why they turned their focus to biomarkers of metabolism. They found enzymes and proteins before people started following the diet that indicate whether they would be successful in losing weight.

Throughout the study, the researchers measured the rate of inhaled oxygen to exhaled carbon dioxide (also known as the respiratory quotient). This served as an indicator of whether fats or carbohydrates are the body’s main fuel. A lower ratio meant the body is burning more fat, while a higher ratio means it is burning more carbohydrates.

“There are people who can be eating very few calories but still sustain their weight because of how their bodies metabolize fuels. It is not for lack of will: It is just how their bodies work,” Dalia Perelman, study co-author, said in a statement. This means that if your body prefers carbs and you are eating fat, it will be harder to burn those calories.

For the researchers, the information obtained from the gut microbiome and protein analysis and the respiratory quotient signatures should be the foundation to create personalized diets. Tracking the amounts of gut microbiome strains would be a good way for people to determine which diets are the most suitable for losing weight in the long term.

However, figuring out what personalized approach works best for everyone is still very challenging. In the meantime, before this becomes a scalable solution, there are still some general approaches we can follow.

For instance, the focus should be on eating high-quality foods that are unprocessed and low in refined flour and sugar. Low-carb diets should be based on monounsaturated fats (such as the ones in avocados) and also high in vitamins, K, C and E, while low-fat diets should be high in fiber, such as in whole grains, the researchers note. A change of approach can also be useful: focus on what you can eat, not on what you can’t.

“Your mindset should be on what you can include in your diet instead of what you should exclude,” Perelman said. “Figure out how to eat more fiber, whether it is from beans, whole grains, nuts, or vegetables, instead of thinking you shouldn’t eat ice cream. Learn to cook and rely less on processed foods. If you pay attention to the quality of food in your diet, then you can forget about counting calories.”

The study was published in the journal Cell.