Today’s prompt, and the companion piece behind it.
The Insulin Response
Why do different people have different insulin responses to the same food?
The Short Answer
Genetics, metabolic health, body composition, gut microbiome, and lifestyle factors all affect insulin response. One person might produce a modest insulin spike from bread while another spikes dramatically. This explains why no single diet works for everyone. Your individual biology determines how foods affect you. The only way to know your response is to observe it, ideally through continuous glucose monitoring or structured self-experimentation.
Something to Sit With
Your body is not the same as anyone else’s. The diet that works for your friend might not work for you, not because you’re doing it wrong, but because you’re different people.
Knowing your own response is more valuable than following general rules.
Learn More
The spectrum of insulin response. When two people eat the same meal, their hormonal responses can differ widely. Studies using continuous glucose monitors have shown that:
- The same food can spike blood glucose (and therefore insulin) significantly in one person while barely affecting another
- Individual responses are consistent: if you spike from bread today, you’ll likely spike from bread tomorrow
- The variation between people is larger than the variation from food to food[1]
This means that glycemic index tables and general dietary advice are averages, useful starting points but not necessarily accurate for you.
Factors that influence response. Several variables affect how your body handles a given food:
Genetic variation: less of it than you would think. Genes influence insulin production, insulin sensitivity, glucose transporters, and enzyme activity. But identical twins show substantially different responses to the same meal, and while heritability estimates run near 30%, the share traceable to known genetic variants is closer to 9%. Most of what separates two people’s responses is modifiable.[1]
Insulin resistance. If you’ve developed insulin resistance (often from prolonged high-carbohydrate intake, excess weight, or sedentary lifestyle), your cells don’t respond well to insulin. The pancreas compensates by producing more, creating larger spikes.
Body composition. Muscle mass acts as a glucose sink. More muscle means more places for glucose to go, reducing the insulin needed to clear it.
Gut microbiome. The bacteria in your gut affect how food is digested and absorbed. Microbiome features help predict glycemic response, though in the larger of the two studies cited here meal macronutrients explained more of the variance than the microbiome did: 15.4% against 6.0%.[1]
Sleep and stress. Poor sleep and high cortisol reduce insulin sensitivity acutely. The same meal after a bad night’s sleep may spike you more than usual.
Meal timing and order. Eating fiber before carbohydrates, or protein and fat with carbohydrates, blunts the glucose and insulin response.
Physical activity. Exercise depletes glycogen and increases insulin sensitivity. A meal after a workout often produces a smaller spike than the same meal eaten sedentary.
The research. A landmark 2015 study from the Weizmann Institute of Science measured glucose responses across 46,898 meals in 800 people.[1] The paper’s own phrase for what it found is high interpersonal variability, and responses were highly reproducible within each person (R = 0.71 to 0.77 across repeated standardized meals).
The researchers were able to build personalized prediction models based on individual factors. The conclusion: population-wide dietary advice misses the reality of individual variation.
Practical implications. This doesn’t mean general guidelines are useless. Reducing processed carbohydrates and sugar helps almost everyone. But it means:
Self-observation matters. Pay attention to how you feel after eating certain foods. Energy crashes, mental fog, and rapid return of hunger suggest your body didn’t handle that food well.
Experiment systematically. If you want to know your specific responses, try a continuous glucose monitor for a few weeks. You’ll quickly learn which foods your body tolerates.
Personalize your approach. What works for someone else may not work for you, and vice versa. Trust your data over general advice.
Further reading:
- Zeevi D et al., “Personalized nutrition by prediction of glycemic responses”[2] — Cell, 2015
- Berry SE et al., “Human postprandial responses to food and potential for precision nutrition”[3] — Nature Medicine, 2020
- Segal E, Elinav E & Adamson E, The Personalized Diet[4] (2017) — Book based on the Weizmann research
- Ludwig DS, “The glycemic index: physiological mechanisms relating to obesity, diabetes, and cardiovascular disease”[5] — JAMA, 2002
Written by AI, directed and approved by me. How this is made →
You already know what to eat
You already know enough.
The information isn’t the problem. You have plenty of information.
The problem is that by the time you’re standing in front of the fridge — tired, negotiating with yourself about whether you’ve earned a snack — it’s already too late. Your habits have voted. Willpower shows up late, outnumbered.
So what if the right thought arrived before all of that?
One thought, every morning, before your day fills in
365 Changes sends you a single prompt about eating. It arrives early — before hunger, before decisions, before habits kick in.
Not a meal plan. Not a rule. Just a question or idea to sit with while you make coffee. Each is simple, but they accumulate.
You need the same core ideas to arrive from hundreds of different angles until they stop being things you know and start being who you are.
Get the daily prompt free:
Here’s what a prompt looks like
Each morning you’ll get a question or scenario like:
You’re in a bad mood and craving comfort food. What do you do first?
Click any of these and read the response — Each one is a complete thought worth reading on its own. The daily email makes sure one arrives before you need it.
- Why do different people have different insulin responses to the same food?
- Humans evolved with natural cycles of eating and not eating. What would your eating pattern look like if you honored that rhythm?
- Why does blood sugar remain stable during fasting even though you’re not eating?
Why daily? Why morning? Why small?
Daily, because change doesn’t happen in one big moment of clarity. It happens through accumulation — the same ideas arriving from slightly different angles until one day you notice you’re thinking differently about something you used to not think about at all.
Morning, because evenings are when you negotiate. Mornings are when you can still hear yourself think. There’s a small window before the momentum builds, before the habits wake up. That’s when a thought can land.
Small, because you’ve already heard it all. You don’t need another article, another tip, another list. You need the right ideas to keep showing up until they stick.
This is not a diet program
There’s no tracking. No streaks. No badges. No notifications begging for attention.
If you open the email, good. If you don’t, it doesn’t guilt you. There’s no streak to break. Tomorrow another one arrives.
One email. It asks almost nothing. It just shows up.
Free. No tracking. No streaks. Just one email, every morning.
Does it work?
Honestly? We don’t know if it will work for you.
I built this for myself. I was tired of feeling like I know exactly what I should eat and never quite eating that way. Tired of the mental math — what I ate, what I’ll eat, what I’m going to eat tonight.
I didn’t need more information. I needed the right thought to arrive at the right time. So I built something that does that, every morning, and I started using it.
It’s working. Slowly. I can’t point to a moment when things changed. I just notice that they have.
—Craig
How this gets made is written down too.
The writing here is done by AI. I direct it, and I approve everything before it publishes. Methods is a journal about the work behind the writing: what gets checked, what gets corrected, and what goes wrong. Methods is free, public, and nothing you have to read.
One way to find out:
Want more depth?
Some mornings the prompt will make you curious. The prompt is complete on its own, but each one also has a companion piece — 3 to 5 minutes of depth, grounded in research, for when you want to understand why.
All 500 companions are free to read. Here are four to start with:
- The Future Self — The person you’ll be in five years is being built by today’s choices
- The Food Mood — You’re in a bad mood and craving comfort food. What do you do first?
- The Tolerant One — You can sit with hunger and discomfort without reacting
- The Self-Deception — In what ways do you deceive yourself about what or how much you eat?
The daily email carries each prompt with its full companion. Subscribe below and it comes to you every morning.