Personalized Nutrition by Prediction of Glycemic Responses
Zeevi et al. (2015)
Intro / Overview:
Depending on who you ask, the dietary guidance you may receive can be drastically different. In recent years, many coaches and professionals have started to give dietary advise based on their beliefs, what has worked for them or what they deem best. However, this isn’t always tailored to the individual, with blanket guidelines being used. One common example of this is the notion that people who are overweight should all go low-carb for fat loss.
In this study, researchers measured the response in glucose levels to 46,898 meals in 800 people to determine if this indicator could help provided personalized dietary guidelines.
Before starting they devised an formula to accurately predict the Personalized Postprandial Glycemic Responses (PPGR; this is the blood sugar response following a meal) to real-life/ normal meals and tested it on a 100 people.
Following these results, they tested 2 diet composed of specific meals. These meals were designed based on the blood sugar response from tests in the 100 people. Diet 1 consisted of “good” meals, e.g. they had a better blood sugar / glycemic response after consumption. Diet 2 was the opposite, coming of what you would class as “unhealthy” meals that spiked blood sugar levels and had a bad PPGR.
The researchers found that individuals showed great variability in their blood sugar / PPGR to the exact same meals or diet. The response one person had to a certain meal could have been similar or completely different than another participant, even though they were eating EXACTLY the same food.
The graph below demonstrates peoples metabolic response following a meal:
If you look at the graph to the right, it shows one individual responded better to a cookie than a banana, where as another participant had the opposite effect.
A Higher Response in Blood Sugar was Associated with Disease Risk Factors:
- HbA1c% (long term blood sugar levels and a key marker in diabetes / heart disease),
- Morning / fasting blood sugar levels (another key risk factor in diabetes / heart disease)
Additionally, larger quantities of unealthy gut bacteria – Proteobacteria and Enterobacteriaceae were associated with higher blood sugar responses / PPGRs.
These observations have been associate with poor glycemic control, and with components of the metabolic syndrome including obesity, insulin resistance, and impaired lipid profile (Blaak et al., 2012; Xiao et al., 2014; Grundy, 2012).
Using an algorithm created from their observations, researchers were able to devise personalized interventions that showed significant improvements in multiple aspects of blood sugar metabolism and populations of health gut bacteria.
Is there a best diet for me?
We know that adherence to any diet is one of the most critical factors in the success of any diet. However, when it comes to getting the most out of your diet, this study seems to show that there is not a “one size fits all diet”.
As I always say: What’s good for one person can be dreadful for another.
For overall health, regulating or reducing the blood sugar response to meals the may be useful in controlling, minimizing, or preventing the prevalence and effects obesity, pre diabetes, type II diabetes, and non-alcoholic fatty liver disease (Grundy, 2012).
Previous research has shown that individuals display different levels of weight loss success based on their metabolic profile (McClain et al., 2013). Individuals who were insulin resistant had much better results when following a higher fat, lower carb approach versus similar participants who followed a high carb/low fat approach.
How To Tailor Your Diet:
Potentially, leaner individuals might want to choose a diet that is lower in fat and higher in carbs as a starting point, whereas someone who is overweight might choose to start with a higher fat, lower carb approach. However, I must stress this is very generalized and their are many factors to consider.
As this study shows, finding the right diet for you will help you to control glycemic responses and maintain high insulin sensitivity – key for long-term health, fat loss and muscle growth. Selecting a diet that is individualized to you may result in better body composition, possibly through improvements in insulin sensitivity (Nassis et al., 2005; Ibanez et al., 2005).
It’s unfortunate that the tools to help you design the optimal diet for yourself are not mainstream at the moment – they require blood testing and a skilled practitioner / medical professional to breakdown and use the data. Never the less, this study highlights the importance of listening to your body and modifying your diet to what makes you feel best.
If you feel sluggish on a high carb diet, or are starting out with more body fat, you may want to try a higher fat approach. But, if a high carb diet gives you consistent levels of high energy and you are starting off leaner, you might be wise to choose the higher carb approach.
This study shows that universal dietary recommendations may not be the best option for overall health or body composition. By personalizing a person’s diet, researchers were able to derive more beneficial metabolic responses over a week long period.
If successful, prolonged individualized dietary control may be useful in controlling, minimizing the effect of, or even preventing chromic health issues. In addition, the possibility exists that this could help us to gain more muscle, lose body fat, and have better overall body composition.