As the warm season approaches, social media fills up with promises of "quick results" and exhausting detox plans. But the truth is simple: sustainable weight management isn't a fight against yourself or short-term starvation. It's a system of habits built on understanding your body's biology: when we give the body what it needs, it becomes easier to create a calorie deficit, so weight can come off more steadily, and the constant battle with hunger is replaced by a feeling of fullness and lightness. fruttberry founder Paulina Gruodienė explains why losing weight starts not with willpower, but with understanding our own biology — and stresses that the key to success lies not in one single detail, but in a comprehensive approach.
More than just a calorie equation
Many people mistakenly think that losing weight is simply a matter of calorie balance (calories in versus calories out). While calorie balance is a necessary condition for weight change, in practice this balance is strongly influenced by biological and behavioral factors. In reality, our body is a complex biological system, governed by hormones and internal processes. When we try to lose weight purely by drastically restricting food, the body adapts: hunger can increase and energy expenditure can drop slightly, making it harder to stick with that kind of regimen over time.
"Weight loss isn't about one 'miracle' nutrient. It's a complex process where energy balance, hormonal regulation, behavior, and even gut microbiota all come together," emphasizes P. Gruodienė.
The 80/20 rule
Weight management should start with a review of what's on your plate. Instead of counting every calorie, it's worth focusing on nutrient density. A balanced diet means every meal should be made up of three main components:
- Quality protein: Chicken, fish, legumes, or eggs help preserve muscle mass (which burns calories even while we rest!) and provide a feeling of fullness.
- Healthy fats: Nuts, avocados, or olive oil support the processes hormones need and help with nutrient absorption.
- Less processed, fiber-containing carbohydrates: These provide steady energy and can help manage appetite, though the overall effect depends on your whole dietary pattern.
The most important rule is the 80/20 principle. 80% of the time, we choose nutrient-dense, whole foods, and 20% of the time we leave room for indulgence. This isn't a universal rule, but for many people it helps reduce psychological pressure and makes it easier to stick with a nutrition plan.
Fiber — the secret "fullness formula"
If diet is the foundation, then fiber is the element that helps you stick to that diet without suffering. P. Gruodienė explains that once soluble fiber reaches the stomach, it absorbs water, swells, and forms a gel that slows digestion. According to her, that's one of the physiological ways to help regulate appetite.
"Fiber isn't a cure-all in this context, but it's one of the few nutrition components whose effect has been consistently confirmed by scientific research. Soluble fiber slows gastric emptying and boosts fullness signals, partly through hormones like GLP-1 and PYY. Clinical studies show that higher fiber intake in the diet can reduce spontaneous calorie intake without conscious restriction. In other words, a person simply, naturally eats less. It's one of the few ways to 'trick' your appetite physiologically, rather than relying purely on willpower," says the fruttberry founder.
She adds that fiber is also an important factor for stable blood sugar.
"For some people, stable blood sugar reduces hunger swings and cravings for fast food. That's especially important for people with insulin resistance, where weight loss often stalls not because of a lack of motivation, but because of biological mechanisms," says P. Gruodienė.
The microbiota: your weight-regulation center
It's also worth remembering that the bacteria living in our gut (the microbiota) may play a role in weight regulation. As P. Gruodienė explains, fermentable fiber is the main food source for these good bacteria.
"Fermentable fiber feeds the good bacteria that produce short-chain fatty acids. These have been linked to better energy regulation and lower inflammation. It's another piece of evidence that weight management doesn't happen only in a 'calorie calculator' — it happens in the gut too," she says.
While fiber isn't a dramatic "fat burner," its effect is steady and cumulative. Scientific meta-analyses show that enriching your daily diet with an extra 10 g of fiber is linked to a small but statistically significant change in weight over the long term.
Fiber is only part of the picture
That said, P. Gruodienė cautions that it's important to stay realistic and understand that simply eating more fiber, on its own, won't make you lose weight. What matters most is a comprehensive approach.
"Fiber won't work if overall calorie intake stays high. If your diet is full of highly processed, calorie-dense food, simply adding fiber won't solve the problem. Supplements also can't fully replace natural food sources, since fiber-rich foods give us other bioactive compounds alongside the fiber itself," she warns.
P. Gruodienė adds that there's a fairly clear consensus among experts on this. Gastroenterologists and obesity specialists emphasize that fiber acts as an "appetite modulator," not as a standalone weight-loss strategy. In practice, that means something simple: for someone moving from a low-fiber diet to 25–35 g a day, it often becomes easier to maintain a calorie deficit without constant hunger.
"Fiber is one of those rare nutritional factors that work on several levels at once: physiological, hormonal, and microbiological. But its real value only shows up when it's part of a bigger system: balanced nutrition, adequate protein intake, physical activity, and sleep hygiene. Weight loss isn't a single lever. It's a whole mechanism, where fiber is an important piece, but not the only one," says P. Gruodienė.
Sleep: the rest during which we "slim down"
While we're used to approaching weight management through action — food or movement — recovery matters just as much. Sleep hygiene directly shapes the choices we make the next day: when the body doesn't get enough rest, the balance of hunger and fullness hormones in the brain gets thrown off. Lower leptin (the fullness hormone) and a spike in ghrelin (the hunger hormone) can increase cravings for calorie-dense food, especially food high in fat and simple carbohydrates.
On top of that, lack of sleep can raise stress hormone levels and indirectly contribute to weight gain, mainly through increased calorie intake and worse choices, especially if it becomes a chronic habit. So a good night's rest is far more than just sleep — it's the time when the body recharges, so that the next morning we wake up calm, energized, and able to choose what's actually good for us.
Physical activity: an important, "invisible" load
Exercise is still often mistakenly seen in society as a punishment for eating pizza, or a way to "make up for" indulgent food choices. But the real value of physical activity isn't in the calories burned — it's in our metabolic health. To achieve sustainable results, it's important to understand that muscle tissue is far more metabolically active than fat, so strength training becomes an investment in the future — the more muscle we have, the faster our metabolism stays, even while resting or sleeping.
But you also shouldn't underestimate simple, everyday movement, what experts call NEAT (Non-Exercise Activity Thermogenesis). This is all the "invisible" activity that doesn't happen at the gym: climbing stairs, walking while on the phone, or even cleaning the house. This spontaneous movement can make up a significant share of daily energy expenditure for some people, and together with regular exercise, it can meaningfully improve the body's sensitivity to insulin. When the body becomes more sensitive to this hormone, fiber and a balanced diet can work even more effectively, creating one cohesive, powerful system on the way to feeling lighter and better.
You can read the full article on ltnaujienos.lt: https://ltnaujienos.lt/gyvenimo-budas/sveikata/kaip-paruosti-kuna-vasarai-be-alinanciu-dietu/
