In our previous article, we saw a clear relationship between blood glucose and hunger — we experience greater hunger when our glucose is lower, and we need food.
- But what about our blood glucose and satiety?
- Does higher glucose after we eat align with feeling fuller?
- Do we want to see a larger rise in glucose after we eat to feel full for longer?
- Or do we want to minimise the rise after eating to maximise satiety?
As you’ll see from our analysis of 82,261 paired glucose and fullness ratings from 4,650 people, the relationship is more complex than you might have realised.
A larger rise in glucose after you eat can indicate that you ate more than you needed to feel satisfied. But, if your goal is fat loss, avoiding type 2 diabetes, or optimising your metabolic health, the amount your glucose rises after you eat doesn’t matter nearly as much as the glucose before you eat.
Read on to learn more.
- What Does the Research Say about the Relationship Between Glucose and Satiety?
- Popular Advice about Stable Blood Glucose
- Post Meal Glucose vs Fullness
- How Did We Collect the Data?
- What is a Typical Rise in Glucose After Eating?
- Why Do Glucose Levels Rise More For Some People?
- Reactive Hypoglycaemia
- Rise in Glucose vs Fullness
- The Problem with Worrying about Your Post-Meal Glucose or Glucose Stability
- How Can I Use My Post-Meal Glucose For Good and Not Evil?
- Action Steps
The research on the relationship between post-meal glucose, fullness and satiety is mixed.
- In a follow-up analysis of their landmark 1995 satiety index study, Susanna Holt and colleagues re-analysed their data and found no significant relationship between post-meal glucose or insulin and satiety or fullness. However, they did find that foods that produced the largest area under the insulin response curve over the two-hour test aligned with greater satiety.
- In a 2016 study, researchers fed 15 healthy young men a light breakfast on two occasions, one of which they infused glucose to keep blood glucose levels high for an hour. Even though the glucose ‘crashed’ lower after the glucose infusion (54 mg/dL vs 70 mg/dL), there was no difference in hunger, appetite, satiety and fullness levels.
- Meanwhile, in a 2021 study with more than a thousand people wearing CGMs, researchers found that people with a larger rise in glucose also had a larger fall in glucose and were motivated to eat sooner and made less nutritious food choices.
Popular Advice about Stable Blood Glucose
One of the tenets of the keto movement was that prioritising fat over carbs keeps your blood glucose and insulin levels lower, thus leading to fat loss. Many people swapped their carbs for fats, believing they would stop producing insulin and thus lose fat.
More recently, with the commercialisation of CGMs for people without diabetes (e.g. Levels, Signos and NutriSense), many have preached the need to keep our blood glucose stable. ‘Clothing your carbs’ with fat can also lead people to consume more energy, gain fat and worsen their metabolic health.
Post Meal Glucose vs Fullness
The chart below shows the relationship between perceived fullness after eating and blood glucose levels.
- As you might expect, people who eat more and see a larger rise in glucose also experience greater fullness when they test (though not necessarily greater satiety per calorie).
- Meanwhile, to the left, people who did not feel full after eating had slightly higher glucose levels.
- Intriguingly, in the middle, the people who felt moderately full had the lowest glucose levels after eating.
What does this all mean, and what are the practical implications?
Read on to learn more.
How Did We Collect the Data?
In our Data-Driven Fasting Challenges, we encourage our Optimisers to track their glucose after eating for the first week to confirm that they are not overfilling their glucose fuel tank with excessive amounts of refined carbohydrates that raise their glucose by more than 30 mg/dL (1.6 mmol).
After you eat, you want to see a modest rise in glucose with a gentle fall below your personalised blood glucose trigger before you eat again.
When they test, we also encourage our Optimisers to reflect on their sensations of fullness after eating and record their perceived fullness in the DDF app (as shown below). Reflecting on their fullness after they eat enables them to identify the foods that empower them to feel fuller for longer vs. those that don’t satisfy and leave them hungry sooner.
For those from a low carbohydrate or keto background, this post-meal testing also enables them to confirm that they are not overconsuming carbohydrates. Hence, instead of fearing or minimising carbohydrates, they are free to focus on their hunger and glucose before eating and identify the meals that help them feel satisfied with lower overall blood glucose levels.
What is a Typical Rise in Glucose After Eating?
The chart below shows the distribution of the glucose change after eating from 4,650 people who have tracked their glucose and hunger after eating in the Data-Driven Fasting app. The average rise in glucose after eating is 15 mg/dL (0.8 mmol/L), but there is a very wide range, from a rise of more than 100 mg/dL to a fall of 35 mg/dL.
The small increase in insulin due to protein, particularly earlier in the day, often helps Optimisers achieve greater satiety per calorie and lower their glucose levels throughout the day.
Why Do Glucose Levels Rise More For Some People?
If you eat a family pizza all by yourself and find your glucose is very high, it doesn’t necessarily mean that you have type 2 diabetes. However, if you continue to eat like that all the time, you might develop type 2 diabetes sooner rather than later.
The chart below of fasting glucose vs rise in glucose gives us some clues about why some people see a larger rise in glucose after eating.
- If your fasting glucose levels are in the pre-diabetic or type 2 diabetes range, you’ll likely see a much larger rise in glucose after you eat.
- However, if you’re metabolically healthy and lean, you’ll see a much smaller rise in glucose after your meals without the crash and hunger many people experience.
A large rise in glucose indicates that you’re overfilling your glucose fuel tank and should cut back on the refined carbohydrates in your diet. But it’s also likely that you have plenty of excess stored fat in your body, so you need to cut back on the dietary fat to allow your body fat to be used for fuel.
Insulin-resistant people will experience a much larger rise in glucose and insulin after they eat. Because their pancreas has to work harder to bring the glucose back down, they often overshoot their normal glucose. This rapidly falling glucose level often leads to increased hunger, eating sooner and poorer food choices.
Conversely, if you’re lean and metabolically healthy, the energy from the carbohydrates in your diet will be quickly absorbed into your bloodstream. Even if you see a large rise from your fruit or oatmeal, the fall afterwards is unlikely to be symptomatic and drive you to make poorer food choices when it comes back down.
For more details, see:
- Glucose Spikes: Your Guide to Healthy Blood Sugars
- Reactive Hypoglycaemia: Avoiding the Blood Sugar Crash
Rise in Glucose vs Fullness
The table below shows our data based on the perceived fullness rating to understand the relationship between glucose rise and fullness.
The columns to the right show that most people feel moderately full after eating. Most of the time, we eat to satiety. Very few people stop eating before they feel at least somewhat full.
The chart below shows the relationship between perceived fullness and glucose rise after eating. To the right, people who eat the most and feel the fullest also see the largest rise in glucose.
But ideally, you want to feel satisfied but not stuffed after you eat. The Okinawans, who are known for their moderate eating and longevity, even have a word for feeling 80% full after they eat: Hara hachi bun me.
Your post-meal glucose can be useful to understand if you ate more than you needed to. If you see your glucose rise more than usual after you eat, you should pay attention to your fullness signals or make better food choices next time.
The Problem with Worrying about Your Post-Meal Glucose or Glucose Stability
The problem with focusing only on your glucose after you eat or maintain stable blood glucose is that it leads many people to swap carbohydrates for fat, which leads to a flatter but a much longer rise in glucose. Rather than tapping into your stored body fat, you’ll be in storage mode much longer as your body tries to burn off all the fat from your last meal.
Worse still is the practice of ‘clothing your carbs’ with fat. This may reduce the rise in glucose after you eat, but fat+carb combo foods tend to be hyperpalatable and leave your glucose and insulin levels elevated for much longer.
Instead of chasing short-term blood glucose hacks to stabilise your glucose, it’s better to prioritise protein, fibre and nutrient-dense foods to increase your satiety per calorie and ensure your glucose returns to normal sooner (i.e. reduce the area under the curve glucose and insulin response).
But rather than fixating on stable blood sugars, it’s better to focus on the things that lead to lower glucose before you eat. A larger rise in glucose after you eat primarily indicates that you have exceeded your Personal Fat Threshold and likely have elevated fasting glucose and insulin resistance.
We ran a multivariate analysis and found that premeal glucose aligns most closely with fasting glucose, a key marker of metabolic health. If you focus on premeal glucose, as we do in our Data-Driven Fasting Challenges, improvements in your post-meal glucose and all the other markers of metabolic health will follow.
How Can I Use My Post-Meal Glucose For Good and Not Evil?
The blue dots on the hourly chart below from the DDF App show the post-meal glucose values. Checking your glucose levels after you eat is a great way to ensure you’re eating until you’re full, but not more than your body needs.
In our Data-Driven Fasting Challenges, most people remember what caused the largest rise in their glucose (e.g. the granddaughter’s cookies or the lunch out with friends where they had the fish and chips).
Learning to eat until you’re full but not stuffed empowers our Optimisers to get at least two robust meals a day while making great weight loss progress, with blood glucose falling below their premeal glucose trigger before each meal.
Meanwhile, people who can learn to eat until they’re only moderately full can even get in three meals a day while losing weight, especially if they’re active and prioritise protein and nutrients when they eat.
- Some rise and fall in glucose is a normal part of healthy appetite signalling. Simply fixating on achieving flatline glucose can lead to poorer food choices.
- But keeping an eye on the glucose after you eat can be a useful tool to train your fullness signals to eat until you are full but not stuffed, thus allowing your glucose to fall back to normal levels sooner.
- If you’re interested in tracking your fullness vs your post-meal glucose levels, we’d love you to take our DDF app for a test drive.
- If you need more help and guidance to optimise your blood glucose and metabolic health, we’d love you to join our next Data-Driven Fasting Challenge.