New analysis of data from a full year Weight loss study Identify the behaviors and biomarkers that contribute to weight loss in the short and long term.
A strict diet—whether it was a healthy low-carb or a healthy low-fat diet—was what mattered for short-term weight loss during the first six months. But people who maintained their long-term weight loss for a year ate the same number of calories as those who regained or did not lose weight during the second six months.
So what explains this difference?
According to the study, the bacteria that live in your gut and the amounts of certain proteins your body makes can affect your ability to maintain weight loss. It turns out that some people shed more pounds on low-fat diets while others did better on low-carb diets.
Stanford Medicine researchers have identified several biomarkers that predict how well an individual will be able to lose weight and keep it off over the long term. These biomarkers include signatures from the gut microbiome, proteins made by the human body, and levels of exhaled carbon dioxide. Researchers published their findings in a Medicine Cell Reports December 13th.
“Weight loss is ambiguous and complex, but we can predict from the start using microbiomes and metabolic biomarkers who will lose the most weight and who will keep it off,” he said. Michael SnyderPhD, professor and chair of the Department of Genetics and co-author of the paper.
Willpower does not lead to weight loss
The data came from 609 participants who recorded everything they ate for a year while following a low-fat or low-carb diet consisting mostly of high-quality, minimally processed foods. The researchers tracked the participants’ exercise, how well they followed their diet, and the number of calories they consumed.
The study showed that simply cutting calories or exercising wasn’t enough to maintain weight loss over a year. To try to understand why, the team turned their focus to biomarkers of metabolism.
“We found specific microbiome environments and amounts of proteins and enzymes at the start of the study period — before people started the diet — that indicated whether they would be successful in losing weight and keeping it off.” Dahlia PerlmanA research nutritionist and co-author of the paper.
Throughout the study, researchers measured the ratio of inhaled oxygen to exhaled carbon dioxide, known as the respiratory quotient, which serves as a proxy for whether carbohydrates or fats are the body’s primary fuel. A lower ratio means that the body is burning more fat, while a higher ratio means it is burning more carbohydrates. Therefore, those who started a diet with a higher respiratory quotient lost more weight when following a low-carb diet.
“There are people who can eat very few calories and still maintain their weight because of how their bodies metabolize fuel. It’s not because of a lack of willpower: it’s just how their bodies work,” Perlman said.
In other words, if your body prefers carbs and you eat mostly fat, it will be much more difficult to metabolize and burn those calories.
“If you’re on a diet that works for someone you know and doesn’t work for you, that particular diet may not be right for you,” added Xiao Li, PhD, co-author of the research. A former postdoctoral fellow in medicine at Stanford University, he is now at Case Western University.
For now, focus on nutrients
Predictive information from the gut microbiome, proteomic analysis, and respiratory quotient signatures lay the foundation for a personalized diet. Snyder said he believes tracking amounts of certain strains of gut microbes will be a way for people to determine which diets are best for weight loss.
We’re not there yet, so until then, according to the researchers, the focus should be on eating high-quality, unprocessed foods that are low in refined flour and sugar.
The research team identified specific nutrients associated with weight loss during the first six months. Low-carb diets should be based on monounsaturated fats — like the one that comes from avocados, rather than bacon — and high in vitamins K, C, and E. These vitamins are found in vegetables, nuts, olives, and avocados. Low-fat diets should be high in fiber, such as found in whole grains and beans, and avoid added sugars.
“Your mindset should be on what you can include in your diet rather than what you should cut out,” Perlman said. “Discover how to eat more fiber, whether it’s from beans, whole grains, nuts or vegetables, instead of thinking you shouldn’t eat ice cream. Learn how to cook and rely less on processed foods. If you care about the quality of the food in your system diet, you can forget about counting calories.”
Christopher Gardnerprofessor of medicine and co-author on the paper, also contributed to this work.
Image from photography rh2010