Not all bodies respond to food the same way—even to the same meal on different days. This post explores the science behind personalized nutrition and why factors like sleep, microbiome, and meal composition can dramatically affect your blood sugar and metabolism. Learn how personalized nutrition can help you optimize your diet, improve metabolic health, and support your gut—starting with real data and actionable insights.
Think about this scenario. You wake up at the same time every Monday morning and follow the exact same routine: bathroom, brush teeth, 8 oz of water, then eat a slice of whole wheat toast with exactly 1 Tbsp of peanut butter. These actions occur over a 30 minute period. The following Monday morning, the exact same protocol is repeated at the same time. You would think that your blood sugar would rise exactly the same after eating the peanut butter toast, right?
Think again.
This is where personalized nutrition comes into play.
What is personalized nutrition?
Personalized nutrition uses your own data to find a precise diet that will optimize your health and functional longevity. Such inputs include existing diet patterns, blood sugar and other biomarker (e.g., cholesterol) levels, gut microbiome make-up, sleep, physical activity habits, environment, and even genetics (Figure 1). Combining these data into a model can be used to provide specific diet and nutrient recommendations that will improve metabolic health.
Back to the peanut butter toast example. Perhaps you only got 5 vs your normal 8 hours of sleep and caused your blood sugar to become very elevated one Monday after eating the toast. Personalized nutrition is about learning which foods impact your metabolism and physiology so you can live a disease-free life.
Real-world data backs this up.
A study by Matthan et al. gave subjects white bread on 3 separate occasions. Did their blood sugar spike the exact same after consuming each bread slice? Well, you probably have guessed that the answer is no! In Figure 2 each line represents one subject and the variation in their glycemic index value following each bread slice. In fact, one female subject had a glycemic index value of 40 after one bread slice, but 120 after another (see upper red circle)! One male subject had a value of 20 after one slice followed by a value of 100 after another (see bottom red circle)! This is called intra-personal variability where adults blood sugar peaks differently to the same food.
Another study conducted by Sara Berry published in Nature Medicine in 2020 found that glucose levels varied by 68% in response to identical test meals among subjects. The number one factor that contributed to this variability was the macronutrient make up of the meals, or meal composition (Figure 3). This includes calories from carbohydrate, protein, and fat, as well as the amount of sugar and fiber. Genetic make-up had the second impact on blood sugar levels, followed by meal context (sleep, previous meal content, activity, meal sequence and meal timing). Notice that the gut microbiome also plays a role! And it doesn’t matter if you are male or female that was the lowest contributor to blood sugar response.
What about our own research?
In my own lab, we found that the microbiome and fiber impacted blood sugar response in females. We were testing the blood sugar and insulin response after eating the following:
- Boiled potato consumed hot
- Baked potato chilled for 5 days and served cold (higher in resistant starch)
The cooked then chilled potato had more resistant starch than the boiled potato. Resistant starch is not broken down in the gastrointestinal tract so it produces less sugar that can be absorbed into the blood. Indeed, the cold potato did reduce blood sugar and insulin compared to the boiled potato. However, 30% of females had a higher blood sugar response after the chilled potato! And 3 microbiome taxa explained the variation in blood sugar response found among the females. This means the microbiome does matter!
There are other considerations for understanding how food impacts blood sugar levels.
· Digestion and absorption of carbohydrate foods varies across adults
· Other nutrients like protein and fat can slow digestion rate that will attenuate blood sugar levels
· So many factors impact blood sugar response like gut microbiome, physical activity, sleep, genetics, and much more!
· What happens the day before matters! Was alcohol consumed? Did you have a rich dessert or eat low-carb all day? Did you run a marathon or binge Netflix on the couch?
Ultimately, personalized nutrition is the future of health. Diet matters! Let personalized nutrition work for you to live your best life! Renutrin® is now offering personalized nutrition services to improve metabolic health, reduce inflammation, and maximize gut microbiome capacity for host health.