Why Fad Diets Fail: The Power of Personal Diet Plans

The science has proven that fad diets are out. Meet the new algorithm that might help lower your blood sugar.

These days fad diets are as common as a kale smoothie. Whether it’s Atkins or South Beach, vegan or gluten-free, there has never been a time where “food labels” were more bountiful.

However many humans following these diets are met with confusion, wondering why they’re gaining weight when their best friends are feeling great. If you’ve ever felt like you’ve been in this pool, scientists may have an explanation for you. It all comes down to an algorithm.

The study’s authors, Eran Segal and Eran Elinav, focused on the glycemic index, or GI, when examining the effects of various diet plans. The GI was constructed as a measure of how certain foods will impact blood sugar; it was assumed that a piece of cake would spike the blood sugar more than a bunch of cherry tomatoes. High blood sugar can lead to anxiety and a cornucopia of other health problems. For decades, many people believed that the GI was a fixed number, but this new study says it’s much more complicated than that.

From The Washington Post:

The researchers recruited 800 healthy and pre-diabetic volunteers ages 18 to 70 and collected data through health questionnaires, body measurements, blood tests, glucose monitoring and stool samples. They also had the participants input lifestyle and food intake information into a mobile app that ended up collecting information on a total of 46,898 meals they had.

The results were full of surprises. Participants had vastly different reactions to a variety of foods, illustrating that there’s not one particular diet that’s perfect for every individual.

Hence the reason why a person could be following the diet rules, and still not seeing any results. This leads to another big issue in how we treat the obesity and diabetes epidemic. Individuals experiencing a lack of success on their prescribed diets sometimes experience shame and confusion, and are ridiculed by society for not having enough “self-control” when, in actuality, they aren’t getting the advice they need.

The important thing is how the type of food reacts with a certain person’s body. Two of the researchers, David Zeevi and Tal Korem examined what factors will influence a person’s blood sugar to spike.

The Atlantic elaborates on some of the conclusions:

These personal differences were influenced by familiar factors like age and body mass index, and also less familiar ones like gut microbes. They found several groups of bacteria, and families of bacterial genes, that were linked to stronger PPGRs.

Using the information gathered, the team created an algorithm to help folks determine what foods are best for their bodies. The algorithm is made up of several factors, for both the human and the food in question. There are 137 factors in total.

The Atlantic continues:

It was remarkably accurate. When the team tested it on a fresh set of 100 volunteers, it predicted sugar spikes that matched the volunteers’ actual data with a correlation of 0.7 (where 1 would be perfect). That’s good: Even if the same person eats the same meal on two different days, the correlation between the two sugar spikes will be 0.77 at most. That sets a ceiling for predictability, one that the team’s algorithm came very close to hitting. It certainly outperformed the crude technique of counting carbs or calories; when Zeevi and Korem tried doing that, they got correlations of just 0.38 and 0.33.

A second study was conducted to help further clarify how the algorithm could provide dietary advice. This experiment involved a personalized dietary intervention for 26 fresh volunteers, with the end goal to reduce post-meal blood sugar levels. Each person as given a “bad” diet and “good” diet, which had been established using the developed algorithm.

The results supported the theory. The good diets worked, by lowering bloods sugar and altering the gut microbiota.

But Segal’s work is far from over. He believes that the algorithm has lots of room to grow, and plans on collecting even more factors about the individuals for the next study.

Interested? You’re not alone. Study participants are no paid, but they are receiving valuable information regarding their bodies and how they should be adapting their eating habits. There’s already 4000 people on the waiting list.  Until then, consider rethinking a diet that might not work for your unique body. 

Photo via iStock


Amanda Kohr is a 25-year-old writer and photographer with a penchant for yoga, food, and travel.  She prefers to bathe in the moonlight rather than the sun, and enjoys living in a state of the three C’s: cozy, creative, and curious. When she’s not writing, you can find her driving her VW Bug, looking for the next roadside attraction or family diner. She also roams the internet at amandakohr.com.