Bio-individuality in Practice: Why Your Friend’s Diet Might Not Work for You
Photo by Dan Meyers on Unsplash
In short: Bio-individuality means that each of us needs something a little different to feel well. Your genes, your gut bacteria, your stress, your sleep, your age, your hormones, your activity and even your culture all change how your body responds to food. That’s why the diet that works wonders for your friend can leave you tired, hungry or bloated. Instead of following one more plan, you can find out what suits you with a simple two-week experiment.
Your friend swears by her morning porridge. You try it and you’re starving by ten. Your colleague feels amazing since she gave up coffee, while you can’t imagine your morning without it. Your sister lost weight on a low-carb diet, and you just felt miserable and dreamed of bread.
Who’s right? All of you.
This is bio-individuality: the idea that each of us has different needs. I explained what bio-individuality is in an earlier article. Today, let’s look at what it means in real life, and how you can find out what your own body needs.
Why doesn’t the same diet work for everyone?
For years, we’ve been told there is one right way to eat. Low-fat, then low-carb, then intermittent fasting, then plant-based, then keto. Each one works brilliantly for some people and not at all for others. That’s not because those people lack willpower. It’s because they’re different.
Science is catching up with what many of us have always felt. In a well-known study from the Weizmann Institute in Israel, researchers measured the blood sugar of 800 people after they ate the same foods. The responses were completely different from one person to the next: some people’s blood sugar rose more after a banana than after a cookie, and for others it was the other way round. A large study led from King’s College London, called PREDICT, found that even identical twins, who share the same genes, can respond differently to exactly the same meal.
So when someone tells you “this is the diet that works”, the honest answer is: it works for them.
What makes your needs different?
Your genes. They influence how you handle caffeine, lactose, fats and even how much you enjoy bitter vegetables. Some people break down caffeine quickly and sleep well after an espresso; others still feel it at midnight. Around two thirds of adults worldwide digest lactose less well after childhood, while many people of Northern European descent digest it easily all their lives.
Your gut. Everyone’s gut bacteria are different, a bit like a fingerprint. They affect how you digest fibre, how much energy you get from food and how you feel after a meal. My 18 FAQs on gut health explain this in more detail.
Your stress and sleep. A tired, stressed body craves sugar and quick energy, and it handles food differently. After a bad night, most of us feel hungrier and less satisfied.
Your age and hormones. What worked at 30 may not work at 50. In perimenopause and menopause, for example, many women need more protein and handle sugar less easily than before.
Your activity. Someone who moves all day, gardens or trains hard needs different fuel from someone sitting at a desk.
Your daily rhythm. Some people wake up hungry, others can’t face food before eleven. Some feel best with three meals, others with smaller ones more often.
Your health history. Food intolerances, medication, past illnesses and digestion all play a part.
Your culture, taste and memories. Food is also pleasure, family, tradition and comfort. A way of eating that ignores this won’t last, however healthy it looks on paper.
How do you know a diet isn’t right for you?
Your body gives you signals all the time. Here are some signs that a way of eating isn’t working for you, even if it works for others:
you’re hungry again an hour after eating,
you feel sleepy or foggy after meals,
you have regular bloating, heartburn or digestive trouble,
you crave sugar in the afternoon or evening,
your sleep gets worse,
you feel irritable, low or anxious,
or you’re constantly thinking about food.
None of these means you’re doing something wrong. They’re simply information. Your body is telling you something needs to change.
A simple two-week experiment
Instead of following yet another diet, become curious about your own body. Here is the experiment I often suggest to my clients.
Step 1: Keep a food and mood diary
For the first week, don’t change anything. Just notice. Write down what you eat and drink, and when. Then, one to two hours later, note how you feel: your energy, your mood, your digestion and your hunger. A few words are enough, for example:
8:00, porridge with banana and honey, coffee. 10:00: starving, a bit shaky, hard to concentrate.
8:00, two eggs, wholegrain toast, tomato, coffee. 11:30: comfortable, focused, not hungry yet.
Also note how you slept, how stressed you felt and how much you moved. These all affect how food makes you feel.
Step 2: Change one thing at a time
In the second week, choose one thing to change based on what you noticed. Only one, so you know what made the difference. For example:
swap a sweet breakfast for one with protein,
have your coffee after breakfast rather than on an empty stomach,
eat dinner an hour earlier,
add a portion of vegetables to lunch,
or leave out wine on weeknights.
Step 3: Notice your sleep
Does a late dinner, a glass of wine or a sweet dessert change how you sleep? Sleep is often where food shows its effects most clearly, and better sleep changes everything else.
Step 4: Listen to your hunger
Before you eat, pause for a moment. Are you really hungry, or tired, bored, stressed or thirsty? There are many kinds of hunger, and my article on the 7 kinds of hunger can help you tell them apart.
Step 5: Look back after two weeks
Read through your diary with a cup of tea. You’ll probably see patterns you never noticed before: a food that always leaves you bloated, a time of day when your energy drops, a meal that keeps you going for hours. These patterns are your personal guide, and they are worth more than any diet book.
What mistakes should you avoid?
Changing everything at once. You won’t know what worked, and it’s very hard to keep up.
Judging yourself. Your diary is information, not a report card.
Copying someone else’s results. What you discover is yours, and it may be different from your friend’s.
Cutting out whole food groups without a reason. If you suspect an intolerance or a health issue, talk to your doctor before removing foods for good.
Thinking it’s forever. Your needs will change with the seasons, your age and your life. That’s normal.
There is no perfect diet, only the right one for you right now
The goal isn’t to find one plan and follow it forever. It’s to learn to listen to your body, understand its signals and adjust along the way. That’s a skill you keep for life, and it’s one of the most freeing things you can learn.
Frequently asked questions
What is bio-individuality in simple words?
It’s the idea that there is no single diet that suits everyone. Each person has different needs depending on their body, health, age, lifestyle and preferences, so the best way of eating is the one that fits you.
Is bio-individuality backed by science?
Yes. Research on personalised nutrition, such as the Weizmann Institute study on blood sugar and the PREDICT study on twins, shows that people respond very differently to the same foods. Genes, gut bacteria, sleep and lifestyle all play a part.
Do I need a DNA or gut test to know what suits me?
Not necessarily. Tests can give interesting information, but a careful food and mood diary, and paying attention to how you feel, already tells you a lot, and it costs nothing.
Can my needs change over time?
Yes, and they will. Age, hormones, stress, the seasons, how active you are and your health all change what your body needs. That’s why it helps to keep listening.
Would you like some help?
Reading your body’s signals isn’t always easy on your own, especially when you’re busy, stressed or have tried many diets before. That’s exactly what I do in my coaching: together, we look at your diary, your life and your goals, and build a way of eating that truly fits you.
Have a look at how we can work together, or book a free 20-minute call. I’d love to help you discover what your body has been trying to tell you.
About Catherine
I’m Catherine Polet, a holistic nutrition health coach, yoga teacher of more than 30 years, autogenic training teacher, author and speaker. I help people find a way of eating and living that suits their own body, online in English, French, German and Spanish, and in person in Southwest France.
