Barcelona nutrition expert warns against carb-cutting, excess protein supplements

Barcelona’s protein obsession is getting pushback from one of the city’s better-known nutrition voices. Laura Isabel Arranz, described in recent coverage as a doctor in nutrition, pharmacist, dietitian-nutritionist and University of Barcelona professor, is warning that trimming carbs while piling on protein is a bad trade for gym-goers, runners and class regulars chasing body-composition goals.

Her message is straightforward: carbohydrates are the body’s primary energy source, and muscles rely on them first. In a city where protein shakes, bars and powders have become part of the fitness routine, Arranz is arguing that the better question is not how much protein can be added, but whether the rest of the plate still supports training, recovery and day-to-day energy. Her nutrition approach, as described on her site, is centered on healthy, anti-inflammatory eating that adapts to each person’s lifestyle and microbiota.

The broader guidance backs up that caution. The World Health Organization says carbohydrates provide the body’s primary energy source and says a healthy diet for most people should get roughly 45% to 75% of daily energy from unrefined carbohydrates. It also warns that excessive protein can place a metabolic burden on the body, particularly the kidneys. That matters in Barcelona’s Mediterranean food culture, where performance goals are increasingly being chased with supplement-driven shortcuts that can crowd out real meals.

The U.S. National Institutes of Health Office of Dietary Supplements says many products marketed for exercise and athletic performance contain protein, amino acids, creatine and caffeine. It also says supplements cannot take the place of the variety of foods that are important to a healthy eating routine. For athletes and recreational exercisers alike, that distinction matters. A tub of protein powder can be convenient after a hard session, but it does not replace carbohydrate-rich meals that refill glycogen and support repeated training.

The trend is not small. Industry research says Barcelona is one of the key Spanish cities driving demand for sports nutrition and protein products, especially among fitness enthusiasts. A market report pegs Spain’s protein supplements market at USD 596.1 million in 2025 and projects it will reach USD 1,106.7 million by 2033. That growth explains why Arranz’s warning is landing now: the real risk is not just overdoing protein, but letting supplement culture push balanced eating out of the routine altogether.