During the first three months of 2025, a university student in Hanoi, Lan, reduced her weight from 82 kg to 72 kg by following a diet that eliminated carbohydrates and fats. However, her skin became dry, her hair fell out in clumps, and her menstrual periods stopped. Three months later, despite maintaining her "spotless" fat-free diet, Lan's weight plateaued at 70 kg. One morning, she fainted in a lecture hall and was rushed to the University Medical Center emergency room. Examination and test results revealed that Lan suffered from endocrine disorders and fatty liver disease.

Nam, 28 years old, who is 1,75 m tall and weighs 95 kg, also eliminated carbohydrates and fats from his diet. His meal plan consisted solely of boiled chicken breast, egg whites, and steamed broccoli, which he called an "absolutely clean diet." In the first month, Nam lost 10 kg. However, by the third month, his muscles began to sag despite regular gym workouts. He experienced insomnia, exhaustion, and lost interest in life. A urologist confirmed that Nam's testosterone levels, the hormone crucial for male vitality and libido, had sharply declined.

Doctors explain that testosterone is synthesized from cholesterol. When the body does not receive enough fat, the production of this hormone is disrupted. A study published in the Journal of Steroid Biochemistry and Molecular Biology indicates that very low-fat diets (under 20% of total energy intake) can reduce testosterone levels in men by 10-15%.

completely eliminating fat and carbohydrates does not lead to rapid weight loss. Photo: Bui Thuy

In Vietnam, approximately 20 million people, accounting for 19,5% of the population, live with overweight or obesity. This number is increasing, and the trend of younger individuals being affected is a growing concern for medical professionals. The World Health Organization (WHO) classifies obesity as a complex chronic disease with far-reaching consequences, from individual health to national economic burdens. In this context, countless unverified weight loss methods are spreading rapidly on social media without scientific validation.

Associate Professor, Doctor Tran Quang Nam, Head of Endocrinology at the University Medical Center HCMC, explains that the core mechanism of obesity is an energy imbalance, where calorie intake exceeds the body's consumption. A modern lifestyle, characterized by hours spent sitting in front of computers, minimal physical activity, and habits of eating fast food and drinking sugary beverages, causes excess energy to be converted into fat tissue. More dangerously, he notes, people often react with unscientific methods that inadvertently lead to weight regain.

According to Doctor Duong Minh Tuan of the Endocrinology and Diabetes Department at Bach Mai Hospital, when the body consumes too much sugar and refined carbohydrates, the liver converts the excess into triglycerides, which accumulate locally. This mechanism causes non-alcoholic fatty liver disease (NAFLD), which currently affects about 25% of the global population. Sugary drinks, milk tea, sweets, white bread, and white rice, rather than cooking oil, are often the direct culprits in many cases.

Doctor Tuan emphasizes that the issue is not about eating less fat, but about choosing the right type of fat. Saturated fats from animal fat, chicken skin, organ meats, and repeatedly fried foods increase low-density lipoprotein (LDL) cholesterol, often called "bad cholesterol." When LDL accumulates excessively, it deposits in artery walls, forming atherosclerotic plaques that narrow blood vessels. If these plaques rupture, they can cause myocardial infarction or stroke. Conversely, unsaturated fats from marine fish, olive oil, avocados, and nuts like almonds and walnuts help increase high-density lipoprotein (HDL) cholesterol, the "cleanup crew" that transports excess cholesterol back to the liver for elimination.

"The goal of a healthy lifestyle is to reduce LDL and increase HDL," Doctor Tuan states.

The fundamental principle of weight loss is a controlled calorie deficit, meaning calorie intake must be less than the body's consumption, including basic metabolism, daily activities, and exercise. However, this deficit does not mean starvation. Reverse dieting is an approach many experts recommend, prioritizing fiber-rich, low-energy foods such as green vegetables, low-sugar fruits, fish, and tofu to prolong feelings of fullness, while still ensuring adequate protein, complex carbohydrates, and healthy fats.

Regular exercise is also essential and does not necessarily require gym workouts. Just 30 minutes of brisk walking each day can increase HDL, reduce triglycerides, and improve sugar and fat metabolism. A meta-analysis in the journal Arteriosclerosis, Thrombosis, and Vascular Biology noted that moderate, consistent physical activity can increase HDL cholesterol by an average of 3-9%.

Replacing soft drinks, milk tea, or bottled juices with plain water is one of the simplest yet most effective adjustments. Water contains no calories, does not cause blood sugar spikes, and helps extend feelings of fullness before meals.

"Weight loss requires a sustainable plan; one should not rush to lose weight too quickly, which can lead to muscle wasting and dehydration," Doctor Nam advises, adding that reducing body weight by just 5-10% can significantly improve blood pressure, blood sugar, blood fat levels, and sleep apnea. If patients experience stress or plateau during weight loss, consulting a psychologist and expert is necessary to manage emotions and maintain motivation.

Thuy An