Why diets don’t work in the long run

There are as many diets and health trends as grains of sand. And yes, you can lose weight with them in the short term, mostly because you stop eating industrially processed food and give your body some relief. But most diets also cut out the healthy carbohydrates we cannot live without. And that approach usually backfires over time. Look closely at what happens in the body during a diet and afterwards, and the long-term damage is often greater than the short-term weight loss — exceptions aside.

There was a long phase when too much fat was blamed for excess weight. Today sugar, and with it carbohydrates, is the root of all evil.

In the seventies a trend took hold in medicine: fat is bad for our health. Fine. So a “low-fat” diet stayed popular for a very long time. I put that in quotation marks, because this diet was low in fat in name only.

To this day the supermarket is full of products labelled “reduced fat”. But that doesn’t make them healthy. The missing fat is often replaced with sugar, salt or other additives, which rarely makes the product any better.

In the past the focus lay on eating less fat, which pushed up the consumption of animal protein — meat and dairy. Yet that way of eating was not necessarily low in fat, because many animal products, cheese and fatty meat above all, carry a lot of it. Lean meat such as chicken breast or low-fat yoghurt really does contain less fat, but at the same time healthy plant fats from nuts, seeds or avocados were often dropped altogether.

The result was a one-sided way of eating that may have done more harm than good, because too much animal fat and protein can burden the liver. At the same time the benefits of small amounts of healthy plant fats, which the body needs, were neglected.

We should also be aware that many foods can hide fat — often more than we suspect. Don’t rely blindly on the fat figures on the packaging, because they are averages. One coconut can contain more fat than the next, one chicken be fattier than another. Just as people store different amounts of body fat, foods vary naturally too.

The figures on the packaging are standardised and apply to a particular batch or to a product’s average. Manufacturers don’t measure the fat content of every single chicken breast or coconut — that simply isn’t feasible. So treat those numbers as a guide, and keep in mind that the actual fat content can differ slightly.

The idea that we humans need large amounts of protein to stay healthy is stubbornly persistent — and it isn’t true. The actual protein requirement is around 0.8–1.2 grams per kilogram of body weight and is fairly easy to meet, on a plant-based diet too.

Another misconception is that only animal products can supply enough protein. In fact many plant foods — pulses, wholegrains, nuts and seeds — are rich in protein and deliver all the essential amino acids when combined in a balanced diet.

A comparison often heard is that large animals such as elephants, gorillas or giraffes live entirely on plants and grow strong and muscular. Such comparisons should be treated with care, though, because these animals have a different digestion and metabolic physiology from ours. They can, for instance, extract nutrients from hard-to-digest plant parts like cellulose, which humans cannot. Still, it shows that plant food can supply protein in sufficient quantity.

One important point many people miss: to build muscle the body needs not only protein but carbohydrates too. Carbohydrates, especially from whole foods such as fruit and vegetables, supply the energy needed for recovery and for building muscle mass. Protein is the building block, but carbohydrates are essential for refilling the glycogen stores emptied during training.

In fact, more and more extreme athletes are turning to a plant-based diet. They report shorter recovery times and better performance, which may be down in part to the anti-inflammatory properties of many plant foods. With the right planning, a plant-based diet can fully cover protein needs even under intense training, and bring further health benefits along the way.

Sugar and carbohydrates have an extremely poor reputation these days. They are often cast as enemy number one, especially in connection with excess weight and metabolic problems. The reasoning? That every form of sugar carbohydrates are made of is just as harmful as isolated sugar, because the body turns it into fat.

Yes, it is true that poor-quality carbohydrates — the kind in white-flour products, sweets or heavily processed food — do little for your health. A slice of cake from the bakery certainly won’t do your body any favours. But high-quality, complex carbohydrates, the kind we find in fruit, vegetables or wholegrains, are a completely different story. The sugar in fruit is not comparable to isolated sugar: the fibre it comes with releases it more slowly, and it behaves quite differently in your body.

The real problem, though, is often the combination of sugar and fat that we take in day after day from most processed foods. Look at the typical examples: cake — sugar and fat. Burgers — sugar and fat. Pasta with cream and chicken — sugar and fat. Pizza, cheese rolls, chocolate bars — this pairing everywhere. It is energy-dense, it burdens the body, and it quickly becomes a habit.

The trend towards eating high in protein and fat but low in carbohydrates continues today. Yet as we already saw in the article “The real cause of weight problems”, healthy carbohydrates are vital for our body. They supply the energy we need for our brain, our muscles and our whole metabolism. A diet high in fat, meanwhile, can burden the liver and cause damage over time.

So it is worth looking more closely and rethinking the role of carbohydrates in what we eat. Not all carbohydrates are alike — and the healthy, complex sources should stay a fixed part of our diet.

Almost all of today’s popular diets follow a similar principle: few carbohydrates, and often more fat and protein instead. They go by different names — low-carb, keto, paleo, glycaemic-index diets and so on — but they usually rest on the same idea: force the body to burn fat by withholding carbohydrates. In one version fruit is off the table entirely, in another you may eat exactly one green apple a day.

Of course we feel better at first on such diets, because we drop heavily processed foods like fast food, fried things, cake or snacks. That alone gives your body short-term relief. But here is what many overlook: these approaches usually don’t address the actual cause of weight problems. Instead they become one more short-term experiment that gets us nowhere in the long run.

I want to say something about the ketogenic diet, which is very much in fashion right now. This way of eating is known for being extremely low in carbohydrates and at the same time very high in fat. The basic idea is that by going without carbohydrates the body is forced to use fat as its main source of energy. It sounds promising at first, especially where losing weight is concerned. But let us look at what actually happens in the body — and why this way of eating can become a problem in the long run.

How does ketosis work?

When you eat almost no carbohydrates, the body first empties its glycogen stores in the muscles and the liver. Once those are used up it switches over: fat metabolism ramps up and the liver produces so-called ketone bodies from fatty acids. Those ketone bodies then serve as an alternative energy source for the brain and the muscles. At the same time the body obtains some glucose from amino acids — that is, from protein — through gluconeogenesis, a metabolic process.

In other words, in ketosis your body switches entirely to burning fat. Sounds efficient, doesn’t it? The only problem: this state is a survival mode the body originally developed for emergencies, for when no carbohydrates are available — during periods of famine, say. It is not a state that is ideal for health over the long run.

The ketogenic diet and weight loss

Yes, the ketogenic diet can lead to rapid weight loss at first. But that initial drop often comes from losing water: as glycogen breaks down, water is released in the body and the scales fall quickly. Actual fat loss does set in as well, but no faster than on any other calorie-reduced diet.

The bigger problem, though, is that this way of eating does not address the cause of weight problems. Losing weight depends — as with every other diet — on taking in fewer calories than you burn. And as soon as you eat more carbohydrates again, the body refills its glycogen stores, and the water that was lost comes back. Many then experience the notorious yo-yo effect.

Why is the ketogenic diet a problem over the long term?

• Nutrient deficiencies: cutting out many carbohydrate-rich foods such as fruit, wholegrains or starchy vegetables can lead to a shortage of important vitamins, minerals and fibre.
• Strain on liver and kidneys: a high intake of fat and protein can put liver and kidneys under considerable strain, especially in people who already have problems. Breaking down ketone bodies can also throw the acid-base balance off.
• Adrenaline and stress: a low-carbohydrate state leads the body to release more stress hormones such as adrenaline in order to provide energy. That may work in the short term, but over time it can overtax the body and lead to hormonal imbalances.
• Carbohydrates matter: carbohydrates are not only a source of energy, they also play a part in regulating hormones and in how the nervous system works. The brain in particular needs glucose to work at its best. A shortage can show up as trouble concentrating, mood swings and loss of energy.

What happens when carbohydrates come back?

Many people fail at the ketogenic diet in the long run because it demands so much restriction. As soon as more carbohydrates are eaten again, the body stores glycogen and water, which is often perceived as putting on weight. The body is then usually less efficient at handling carbohydrates as well, because the metabolic processes for it were dialled down.

Why I see the ketogenic diet critically

The ketogenic diet can help with losing weight in the short term, but it offers no lasting solution. It rests on a survival mechanism of the body that is not meant to be a permanent state. On top of that, it can strain the body over time and withhold important nutrients. A balanced diet that combines healthy carbohydrates, good fats and enough protein is a far more sustainable and health-promoting alternative. Your body needs carbohydrates — not only to survive, but to function at its best.

With intermittent fasting too, many people report positive effects. They feel more energetic, clearer in the head and often fitter as well. Why is that? One of the main reasons is that during the fasting phase the body has to spend less energy on digestion and instead activates processes such as autophagy. That means cells are cleaned out and repaired — a natural mechanism triggered by longer breaks between meals.

Another advantage: during the fasting phase the glycogen stores are emptied and the body starts drawing on fat reserves. That can improve insulin sensitivity and steady blood sugar. But there are aspects worth looking at more closely too.

When we eat nothing for a longer stretch — neither fat nor carbohydrates — blood sugar falls. To provide energy, the body releases stress hormones such as adrenaline and cortisol. In the short term that can feel like a high, because those hormones make us more alert and focused. At the same time the liver produces ketone bodies that supply the brain with energy, which many perceive as a “clear head”.

But here is the crux: for people with an already burdened liver, hormonal problems or chronic illnesses, this heightened release of stress hormones can put extra pressure on the body. Especially when the body already struggles to regulate stress, fasting can do more harm than good. A permanently raised adrenaline level burdens not only the liver but the nervous system too, and can lead to exhaustion over time.

On top of that, during fasting there is no supply of glucose, which the body needs for many processes. Healthy people can close that gap through gluconeogenesis, the making of glucose from the body’s own substances, but a body that is already weakened may struggle to cover that energy demand.

In short: intermittent fasting can be a good method for many people to regulate the metabolism, give the body relief and support health. But it matters to take your own physical condition into account. A body that is already burdened can experience additional stress from the hormonal shifts of fasting. So everyone should weigh up individually whether and how this method fits into their own day-to-day life.

As I said, a diet can work really well at first. You lose weight, you may even feel full of energy — for a while at least. But then it happens: your body starts crying out for glucose. Because glucose is what keeps us alive, the main source of energy for your brain and many other processes in the body. And when it is missing, your body switches into emergency mode. The alarm bells ring, and sooner or later comes the point where the cravings hit.

Those moments feel as though you had lost control — you eat anything that delivers quick energy. Afterwards comes the guilt: “Why couldn’t I keep myself in check?” It is a vicious circle many never get out of. But the real mistake is not yours, it is the diet’s, for denying your body the energy it needs.

On top of that, a diet high in fat and low in carbohydrates does more harm than good over time. Too much fat — especially from animal sources — burdens your liver and can affect your blood lipid levels negatively in the long run. The heart does not literally have to “work harder” to pump fat-rich blood, but the whole circulation suffers if this way of eating becomes a permanent state.

What does the body need instead? The answer is simple: glucose. The healthy carbohydrates in fruit, vegetables and wholegrains are what supply your body with lasting energy. These carbohydrates help you break the vicious circle of cravings and frustration. And no, that does not mean fat has to be banished entirely — good fats from nuts, seeds or avocados belong there in moderation. But this trend of programming the body onto almost nothing but fat and protein is no long-term answer.

Let’s be honest: do you really want to put your body through that? Or would you rather give it what it actually needs? Reduce the unnecessary fat load, give your body glucose — and you will see how much better you feel. Your body is not your enemy. It wants to help you, but you have to give it the right tools.

Finally I want to raise an important point that many diets overlook: losing weight can demand a lot of the body, because breaking down fat reserves also releases stored pollutants. Those substances have to be processed and excreted through the liver, the kidneys and other organs of elimination. If the process runs too fast it can overwhelm the body, especially when those organs are already burdened. That is why it matters to lose weight slowly and sustainably, and to support the body with enough nutrients such as antioxidants and with fluids, so that it can manage this process safely.

Do you know the feeling? One of those diets is behind you, you have lost a few kilos and at first you feel wonderful. And then it happens: everyday life catches up with you, the craving for your favourite dishes grows stronger — and bang, everything is back the way it was. Why? Because this kind of diet simply cannot be kept up. Your body needs energy, and if it doesn’t get it from healthy carbohydrates it will eventually make itself heard, loudly.

And what comes next? The dreaded yo-yo effect. You go back to eating as before and, just like that, the weight is back — perhaps even more than before. No wonder, because the actual causes of your weight problem were never addressed. Only the symptoms were tinkered with.The biggest problem? These diets ignore the psychological side completely. Our eating habits, our behavioural patterns — they don’t simply vanish because we skip bread or pasta for two weeks. Instead we sit on a carousel of “I feel amazing!”, “Damn, I failed …” and “Tomorrow I start again!”. And honestly: who wants to feel like that all the time? Many people connect eating with emotions such as comfort, reward or joy — and diet plans ignore that side entirely too.

What we are missing is an approach that meets us as whole people. One that understands that losing weight is not only a question of calories, but also depends on how we think, feel and act. On top of that, every person is different, with an individual metabolism, different hormonal conditions and different ways of living. There is no one-size-fits-all solution. What really works is strengthening the body, tackling the cause and building healthy habits for the long run.

In the end it all comes down to this: there is no diet that works in the long run — at least none that makes you happy. Why? Because every diet involves going without. And honestly, who keeps that up? Exactly. Nobody.

If you really want to bring your body into balance, you don’t need short-term diets but a way of eating you can love — one that gives your body everything it needs. What does that mean? A varied, whole-food diet with plenty of complex carbohydrates, little but high-quality fat, a moderate amount of protein and a decent helping of nutrients, vitamins, minerals and antioxidants. Where do you find all that? In fresh foods such as fruit, vegetables, leafy greens, berries, wholegrains (gluten-free by preference), pulses, nuts and seeds.

The most important thing: eat fresh, unprocessed food and strike industrial sugar and trans fats off your menu. If you can’t do without animal products, at least cut them back drastically and pay attention to quality. Your body will thank you.

And listen to your body: eat when you are genuinely hungry, and don’t overdo it. When your body gets what it needs — without being overloaded — it will find its own balance. With enough nutrients and regular breaks for digestion it begins to recover. And yes, then you will lose weight more easily, hold your comfortable weight and simply feel better. And if you also reduce stress, get enough restful sleep and move your body, the whole thing can go much faster still. But don’t forget to be gentle and patient with yourself and your body along the way. Change takes time.

As with everything in life, the right measure is the key. It is not about perfection, but about a balance you can live every day — without stress and without going without.

If you would like to know a little more about the causes of weight problems, my article “The real cause of weight problems” offers an interesting alternative perspective.