Lots of people are looking for that perfect new diet fad that will help them shed unwanted pounds — but a new study is throwing cold water on that idea.

It appears that one-size-fits-all diet plans are just a bad idea is someone wants to lose weight, as our bodies have different responses to the same foods, according to a Reuters report.

It appears, based on a study out of Israel, that when two people eat the same meal, it may result in a spike in blood sugar levels for one person but not the other, and a consistent spike in blood sugar can result in obesity and diabetes.

That’s bad news for those hoping that one of the fad diets like Atkins or South Beach will solve their weight problems. These diets are based on the glycemic index, which ranks foods on how fast they raise blood sugar after meals in an attempt to help diabetics. This was in an attempt to help everybody on the diet keep blood sugar low and therefore lose weight. But the study in fact found that different people had different responses to the same food.

Eran Segal and Eran Elinav of the Weizman Institute of Science in Rehovot told Reuters that, “The idea behind the low-GI diet is that the glycemic response to a certain food is an intrinsic property of the food which means that we should be able to predict how a certain individual would respond to some food by looking at the average response of a small group of other people to that food. … Our study demonstrates that this cannot be done.”

The researchers examined 800 adults using health questionnaires and also taking measurements of the body as well as stool samples, blood tests, and glucose monitoring. They also examined the food they ate over nearly 50,000 meals.