From Buchinger to protein fasting: How modern diets reshape calorie restriction

Fasting has evolved into various structured methods, each with distinct rules and health claims. Among the most established is the Buchinger fasting technique, created nearly a century ago. Today, modern adaptations like fasting-mimicking and high protein foods offer alternative approaches to calorie restriction and detoxification.

The Buchinger fasting method began in the 1920s when German physician Dr. Otto Buchinger treated his own rheumatism through fasting. After his recovery, he founded a dedicated clinic and wrote key texts on therapeutic fasting. Clinics such as Buchinger Wilhelmi—now in its fourth generation—still offer the original method as a core treatment. Courses, like a 7-day Buchinger fasting and yoga retreat on Spiekeroog island in February 2026, also teach the practice.

Before starting Buchinger fasting, participants prepare with two days of light meals, such as vegetables or porridge. The fast itself lasts five or more days, allowing only vegetable broth, diluted juices, small amounts of honey or maple syrup, and fluids. To protect muscle, a protein source like buttermilk is permitted. However, medical supervision is recommended due to the extreme calorie deficit and the use of enemas to clear the intestines. Without a balanced diet afterward, weight loss may be temporary, leading to the yo-yo effect.

Fasting-mimicking takes a gentler approach over five days. Calories drop gradually on the first day, then stabilise at around 750 kcal for the remaining four. The diet includes low-starch vegetables, easily digestible fruits, plant-based drinks, nuts, and whole grains. This method allows more flexibility in timing and a less abrupt shift into fasting.

Protein fasting blends intermittent fasting with protein intake. Followers maintain an 18:6 schedule—eating within a six-hour window and fasting for 18. During the fasting period, protein shakes help reduce cravings and prevent muscle loss.

Each fasting method carries specific guidelines and potential benefits. Buchinger fasting remains a medically supervised option with deep historical roots, while fasting-mimicking and high protein foods provide more adaptable routines. Results depend on consistent dietary habits after the fasting period ends.