Photo by sarandy westfall on Unsplash
In short: Your body turns food into energy, uses what it needs straight away and keeps the rest for later, first as a small quick reserve and then as fat. It draws on those reserves when it feels safe and well fed, and it holds on to them when it senses a shortage. Hormones, sleep, stress, muscle, age and your genes all have a say, which is why eating less and less so rarely works. Most people need more nourishing food, not less.
You have tried the soup week, the no-carbs month and the plan your colleague swears by. Each time, something moved for a little while, and then your body seemed to dig its heels in. You were hungrier, more tired, a bit short with everyone, and the bathroom scale became the judge of your whole day. Somewhere along the way you started to wonder whether your body was working against you.
It isn’t. Your body is doing exactly what it was built to do: keep you alive and well with whatever you give it. Once you understand how it uses and stores energy, a lot of what felt like failure starts to make sense. So here is the physiology, in plain words, and without a diet attached.
How does your body use the food you eat?
Everything you eat is broken down in your digestive system into small building blocks. Carbs become glucose, the sugar that travels in your blood and feeds your cells. Protein becomes the material your body uses to repair muscles, skin and much more. Fats become fatty acids, which are both a fuel and a raw material for your hormones and your cells.
Your body uses energy all day and all night, even when you are sitting still. Most of it goes on the quiet work you never notice: keeping your heart beating, your brain thinking, your body warm, your cells renewing themselves. Then comes digestion itself, which also takes energy. Moving, from carrying the shopping to a yoga class, comes on top of all that.
How does your body store energy?
When a meal brings more energy than you need right then, your body puts some aside. First it fills a small reserve of glucose in your liver and your muscles. This is the quick reserve, the one that carries you between meals and through the night.
When that reserve is full, the rest is kept as fat. I’d like you to read that without any judgement, because fat is not a mistake. It is your body’s savings account, and it also cushions your organs, keeps you warm and helps to make hormones. A body that stores is a body that works.
How does your body burn fat?
Between meals, while you sleep and when you move, your body goes back to its reserves. It starts with the quick one. When more is needed, fat cells release some of what they hold into the blood, and your muscles and organs use it as fuel. This happens every day, to everyone, without any special effort.
Your body also produces heat when it works: when it digests a meal, and when your muscles are active. That is one reason why a real meal and a walk leave you feeling warm and awake, and why muscle matters so much. Muscle is living tissue that uses energy even at rest, a little like an engine that keeps ticking over.
Why doesn’t eating less and less work?
This is where the simple sum of “eat less, move more” falls short. Your body cannot tell the difference between a diet and a time when food has run out. When it receives much less than it needs for a while, it protects you. It becomes careful with energy, so you feel cold and tired. It turns the hunger signals up and the fullness signals down, so you think about food all day. And it may take what it needs from your muscles, which is the last thing you want.
Then the diet ends, as diets do, and a body that has been through a shortage is very keen to rebuild its savings. I wrote about this in more detail in what crash diets do to your body and mind.
In my coaching, I see things the other way round. Most people need more nourishing food, not less: more vegetables, enough protein, healthy fats, proper meals at regular times. A body that is fed well and regularly feels safe, and a body that feels safe has no reason to cling to its reserves. You can read why in why you need more food, not less.
What do hormones have to do with it?
A great deal. Hormones are the messengers that tell your body what to do with the energy you eat, and two of them are worth knowing by name.
Insulin
Insulin is made by your pancreas. When glucose arrives in your blood after a meal, insulin opens the door of your cells so the glucose can go in and be used, and it sends the surplus into storage. When meals are very sugary or made mostly of refined carbs, glucose arrives all at once, a lot of insulin follows, and a couple of hours later you feel flat and hungry again. Over the years, cells can start to respond less well to insulin, and the body then stores more easily. A meal that combines vegetables, protein, healthy fats and whole carbs is digested more slowly, and the whole system stays calmer.
Leptin
Leptin is made by your fat cells. It tells your brain how much you have in reserve and, in simple terms, says “we have enough, you can stop eating”. When you eat too little, leptin drops and hunger grows. When the body has carried larger reserves for a long time, the brain can become less sensitive to the message, so you feel hungry although there is plenty in store. Neither has anything to do with willpower.
Stress and sleep hormones join the conversation too. A short night or a tense week changes your appetite the next day, as I explain in how sleep and stress affect your appetite and weight. And if you’d like to support the whole orchestra through everyday habits, have a look at six daily habits that support your hormones.
Do genes and age decide everything?
They have a say, and it helps to be honest about that. Some people are built slim and stay that way with little effort. Others carry more easily, or have a bigger appetite, or keep their reserves around the middle or on the hips, just like their mother did. Your body has its own shape and its own way of working, and no plan will turn it into someone else’s. That is bio-individuality, and I describe it in why there’s no one right way to eat.
Age matters as well. Over the years we tend to lose a little muscle and to move less, and for women the hormonal changes around menopause shift where the body keeps its reserves. None of this is a door closing. Muscles respond to being used at any age, and regular, nourishing meals with enough protein help you keep them.
So genes and age set the frame. Inside that frame, how you eat, sleep, move and rest makes a real difference to your energy, your mood and how at home you feel in your body.
What helps your body feel safe and well fed?
Here is what I suggest, and none of it involves counting anything.
Eat real meals at regular times. Three meals a day suit most people. Skipping lunch and arriving home starving is the surest way to an evening in front of the cupboard.
Add before you take away. More vegetables on the plate, a source of protein at each meal, a little olive oil, a handful of nuts. When the nourishing foods take up more room, the rest takes up less, all by itself.
Choose whole carbs. Oats, wholegrain bread, brown rice, lentils, potatoes in their skins. They release their energy slowly and keep you going through the afternoon.
Listen for hunger and fullness. Your body tells you when it needs food and when it has had enough, if you slow down enough to hear it. I explain how in how to recognise your hunger and fullness cues.
Use your muscles. Walk, carry, climb the stairs, garden, practise yoga. Choose something you enjoy so that you keep doing it. There are gentle ideas in my article about exercise.
Protect your sleep. A rested body regulates appetite far better than a tired one.
Be patient and kind. Your body changes slowly, in both directions. Notice your energy, your digestion, your sleep and your mood: they tell you much more than the scale does.
Try this today: at your next meal, look at your plate and ask one question only. Is there something here that truly nourishes me? If the answer is no, add something. That’s all.
Frequently asked questions
Why does my body hold on to weight when I eat less?
Because your body reads a long stretch of too little food as a shortage. It becomes more careful with energy, you feel colder, more tired and hungrier, and it protects its reserves. It is a protection, not a fault, and it usually eases when you eat regular, nourishing meals again.
Does my metabolism really slow down as I get older?
What mostly changes is how much muscle you carry and how much you move, and both tend to go down gently over the years if we do nothing about them. Using your muscles regularly and eating enough protein at each meal helps your body stay lively at any age.
Is my weight decided by my genes?
Your genes influence your build, your appetite and where your body likes to keep its reserves, so bodies will always differ. They do not decide how you eat, sleep, move and rest, and those daily habits shape how you feel far more than you might think.
Which foods help my body use energy well?
There is no magic food. What helps is a real meal with vegetables, a source of protein, some healthy fats and whole carbs, eaten at regular times, so your blood sugar stays steady and your body feels safe.
When should I talk to my doctor?
If your weight changes quickly without an obvious reason, if you feel exhausted, very cold or unusually thirsty, if your periods change suddenly, or if food and weight take up a lot of space in your thoughts, please see your doctor. Questions about medication of any kind are for your doctor too.
Would you like some help?
Learning to feed your body well, without diets and without counting, is one of the things we work on in my group programmes in nutrition and health, such as Six Tuesdays in Montignac. If you’d like to hear when the next group opens, write to me at hello@catherinepolet.coach.
Would you rather work one to one? I also coach online. Book a free 20-minute call, and we can look together at what your body is asking for, at your own pace and with kindness.
About Catherine
I’m Catherine Polet, a holistic nutrition health coach, yoga and autogenic training teacher for more than 30 years, author and speaker. I help people find a way of eating and living that suits their own body, online in English, French, Spanish and German, and in person in Southwest France.
