Is Your Microbiome Undermining Your New Year's Resolution?

University studies – and informal surveys of our friends and family – clearly show that the number one New Year’s resolution is to lose weight and be healthy. Year after year, people garner their resolve, join the gym, research the Paleo diet, Atkins, veganism – and vow that this year will be different. This time, the diet will work.

And yet, unfortunately, most dieters ​don't succeed. Still, we all know someone who committed to a diet and did get healthier – so why doesn’t everyone achieve the same results?

The Weizmann Institute of Science has found the answer. And the good news is, it’s not your fault. It’s your microbiome’s.

The microbiome is comprised of trillions of bacteria, fungi, and viruses, all living together in our gut, where they form a complete ecosystem that is critical for our health.

Immunologist Dr. Eran Elinav and computer scientist Prof. Eran Segal use their diverse skills to investigate the microbiome as part of their Personalized Nutrition Project, or PNP (www.personalnutrition.org).Their most recent nutrition study – the largest of its kind, with 800 volunteers – was unusual in that it included analysis of each person’s microbiome. (Read more about the study here.)

Study participants were outfitted with small monitors that constantly measured their blood sugar levels. They were asked to record everything they consumed, as well as lifestyle factors such as sleep and physical activity. Overall, the researchers assessed bodily responses to more than 46,000 meals. After gathering these reams of data, the scientists developed an algorithm able to predict a person’s response to food, based on their lifestyle, medical background, and the composition and function of their microbiome.

The team’s primary metric was glucose levels, as high blood sugar can lead to obesity, diabetes, and other damaging conditions. The study results were a surprise: people responded differently to the same foods, including having a “healthier” response to foods that we think of as not nutritious.

Take sushi and ice cream, for example – it seems reasonable to assume that everyone would react similarly to eating these foods, such as having a glucose increase after eating ice cream. And that assumption was accurate – for some people. Many others had the opposite response; their blood sugar spiked after eating the presumably healthier sushi, but remained level after ice cream.

But how will this research, and the personalized diets that result, help those of us who weren’t lucky enough to be part of the research?

In a follow-up study with a fresh cohort of 100 volunteers, the algorithm was indeed able to predict a blood sugar rise in response to different foods, demonstrating that it can be applied to new participants. Dr. Elinav and Prof. Segal found that there could also be different responses to the same foods within an individual, due to lifestyle ​factors; for example, ​eating an apple may affect one’s blood sugar levels differently depending on whether it was consumed after exercise or sleep.

In other PNP findings, Dr. Elinav and Prof. Segal revealed that artificial sweeteners, so ubiquitous in today’s diet, may actually lead to the conditions, such as obesity and diabetes, they were supposed to help prevent. The breakthrough made headlines across the globe.

The scientists are working to move the PNP beyond Israel. In the meantime, until we can get our microbiomes analyzed and have a personalized diet, one of our New Year’s resolutions will be to not compare our weight-loss success to that of others.