Abstract
A ketogenic diet (KD) is increasingly debated as a countermeasure against nutrition-related modern diseases. While being immunologically beneficial, KD is still suspected of having severe metabolic side effects and negatively impacting general well-being, which prevents its widespread clinical use. We conducted a prospective pre-post interventional study investigating the effects of an eucaloric KD on metabolism, weight loss, body composition, diet adherence, and quality of life. The study had two stages: first, feasibility was tested in healthy, normal-weight participants over three weeks. After positive results, the KD period was expanded to three months, enrolling adults with overweight. Significant weight loss was observed in both groups, reducing body fat without affecting muscle or bone mass and without adverse metabolic changes. Quality of life improved, and fatigue symptoms in subjects with overweight decreased. These findings may help to overcome reservations about KD, encouraging its use as a medical tool for treating nutrition-related disorders.