No One Diet Works for Everyone – Here’s Why

Why has the perfect diet that works for everybody not been found yet?

Why does one diet work perfectly for some people, but not for others?

Are we missing something obvious?

This is the question Professor Eran Segal at the Weizmann Institute of Science in Israel set out to answer.

He does a wonderful job explaining what they know and how they can apply that knowledge to diet customization:

Factors Making Tailored Diets a Necessity

Professor Segal is of the opinion that so many different types of diets are touted to be the best, but the boasts are based on opinion rather than on hard, scientific evidence that they actually are.

With the statistical knowledge that a huge percentage of the American population is diabetic, pre-diabetic and/or has fatty liver disease, and that much of this is due to diet, this needs to be addressed.

Differences in genetics, lifestyle and an individual body’s good bacteria all play a significant role in how different people’s bodies respond differently to different diets.

Just as a woman would most likely never consider buying a one-size-fits-all wedding dress (probably why there is no such thing) nutrition also must be tailored to fit a particular individual.


Why Do Certain Foods Make Your Blood Sugar Spike?

The traditional belief is that foods with a high GI (Glycemic Index) make blood sugar spike, in other words these foods are high in glucose or carbohydrates that get absorbed into the bloodstream.  For example pure glucose would be rated at 100 as it would translate to a direct glucose injection into the blood stream.

Why do carbohydrates have a high GI index?

Because theoretically carbs get metabolized into glucose that end up in your blood stream. Foods with little or no carbs are rated at a low GI.


Does a One-Size-Fits-All Approach Work?

After telling many people about the individualized approach of Dr Segal, many still cling to the belief that all high fibre/protein dishes are good for everyone, and all starchy foods are bad for everyone.

According to research by the Weizmann Institute, computing a GI for a food substance is a generalized approach that does not take the individual eating it into account.


From testing my own experimental blood sugar measurements, I have found that brown rice causes a spike in my post-dinner blood sugar, while fries from the local fast food chain caused my sugar count to stay flat. Guess which one would make me gain weight!

When testing the GI of a group of people after having an apple, the measurements ranged from 45 to 90!


No One Diet Works for Everyone Heres Why Choice


Why Is a Spike in Blood Sugar Bad After Your Meal?

Having constant blood sugar spikes after meals can lead to a whole heap of complications.

As soon as blood glucose goes up too high, the brain picks this up and prompts the pancreas to release insulin. Insulin are the little soldiers that attempts to normalize glucose in the blood. It does this by making the cells absorb sugars for energy, but if the glucose levels are too high, it turns glucose into fat for storage, and that’s how you get fat.



Dr Eran Segal and Eran Elinav conducted a study with 1000 people to monitor their blood-glucose levels before and after meals, and continuously for a full week.

Since most people eat three meals a day, they were able to monitor the effects of 50 different meals a week per person. The key findings of the study were that different people responded very differently to the same meals.

Sometimes the results of the same foods with different people were entirely opposite. What made some glucose levels rise made others drop. Blood-glucose levels that were extremely high after the same meals with certain people had no effect at all on others, minimal and medium rises in glucose levels on other individuals and even dropped below normal with others.

This is the evidence that it isn’t just the food being consumed that is the problem, but how an individual reacts to it.

The next step was to try to find what about the individual is making the difference in the sugar metabolism. Of course, factors such as height and weight were considered. There were also blood tests, medical background, etc.

Gut bacteria which helps to digest food was the most interesting component they examined, and found that this greatly helps to explain the variability of the study’s results.

The good bacteria increased when people were on the right personalized diet, while the bad bacteria that causes disease decreased. This may have profound implications for cures of many ailments, including diabetes.


The Bottom Line

There is scientific reason to know for sure that there is no single, best diet for everyone.

If your dieting efforts have failed even when you scrupulously followed the various diets you’ve tried, it doesn’t have anything to do with failure on your part.

Even if you didn’t give into the temptation to eat when a diet that was bad for you increased your hunger, it would still result in weight gain or no loss of weight at all because the foods raised your glucose level too much for the diet to work.

It actually doesn’t have anything to do with the failure of the diet itself in many cases, either. According to the findings of this study, diets that failed for you might be very successful for others even if they don’t follow them as closely as you had.

Dr Seagal & Dr Elinav’s Book can be found below:

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