Science finally explains why you and your bestie can follow the same healthy diet but get totally different weight loss results


"I'm doing everything right! Why aren't I losing weight?" It's one of the most common complaints about dieting, particularly from women. Even when you follow a diet exactly as it's written, your weight loss may vary widely from what the diet guru says it should be-or even from your friend on the exact same plan. So what gives? How we metabolize healthy food can be very different from person to person, according to a new study, published in the journal Cell. Translation: You and your friend can eat the exact same meal and end up with totally different results.

To see how different bodies responded to eating the same foods, the researchers closely monitored 800 adult men and women for a month. Participants had to eat standardized meals given to them by the researchers and wear a device that constantly monitored their blood sugar, in addition to submitting to other tests, questionnaires, and reporting practices.A total of 46,898 meals were analyzed, and the results were shocking.

"There are profound differences between individuals," said Eran Segal, Ph.D., co-author of the paper and a professor at the Weizmann Institute of Science in Israel. "In some cases, individuals have opposite response to one another, and this is really a big hole in the [obesity] literature." (P.S. Certain Body Types Have Been Linked with Health Conditions.)

And these differences in digestion didn't just apply to junk foods. Even healthy foods provoked different responses in some people. The study used the example of a woman who was obese and diabetic despite trying to lose weight on every diet under the sun. During the study, the researchers noticed her blood sugar spiked after eating tomatoes-a food she thought of as healthy and ate several times a day in various forms. Once they removed tomatoes from her diet, she began to see results. This doesn't mean tomatoes are unhealthy, Segal cautioned, just that they were for this one woman.

The study's finding open up the possibility of creating individualized diet plans tailored to your unique metabolism, gut bacteria, blood sugar, and other biomarkers, the researchers said. (Find out 6 Ways Your Microbiome Affects Your Health.)

"Maybe we're really conceptually wrong in our thinking about the obesity and diabetes epidemic," Segal said. "The intuition of people is that we know how to treat these conditions, and it's just that people are not listening and are eating out of control-but maybe we were giving them wrong advice."

And while this all sounds very high-tech, it may be something many of us have already been doing through trial and error. We all have friends, for instance, who swear they can only lose weight on a low-carb diet, while others maintain that they feel their best on a high-carb vegan diet. They could both be totally right, according to this research. So instead of signing everyone up to wear a glucose monitor around the clock, perhaps we should be teaching people to listen to their bodies and trust how they're feeling. If we can learn what truly good health feels like and how to pick foods that help us feel that way, then maintaining a healthy weight might just get a lot simpler. (In the meantime, try the Best Diet Plans for Lasting Weight Loss-as proven by science.)