Takao Hospital in Japan is widely recognized for pioneering the low-carbohydrate diet (LCD), but it initially promoted a diet of brown rice, fish, and vegetables starting in 1984, likely making it the first hospital in Japan to include brown rice in patient meals. In 1999, it became the first to introduce the LCD. Currently, inpatients with atopic dermatitis can choose between the brown rice, fish, and vegetable diet or the LCD, while diabetic patients are prescribed only the LCD.

The first author, K.E. below, became interested in dietary habits following a phone call in May 1984. As a former member of the All-Campus Joint Struggle Committee (Zenkyoto), K.E. was contacted by a friend from Kyoto University days at Takao Hospital. The friend requested assistance with health management for students staging a hunger strike outside the department store Takashimaya to protest the unconstitutional docking of a U.S. nuclear submarine carrying Tomahawk missiles at Sasebo. The students planned to consume only water during their protest.

In 1984, Takao Hospital, staffed by unique figures like a former Zenkyoto doctor and a nurse with a past as an Arab guerrilla, was familiar with unusual requests. At the time, K.E., a 34-year-old practitioner of Western and Chinese medicine, faced a new challenge: supporting a hunger strike by Kyoto University students protesting the docking of a U.S. nuclear submarine. K.E. had no experience with patients nearing starvation and found little relevant literature. He soon realized that a hunger strike was akin to fasting, a practice with historical roots in Japan, including a key 1930 study about fasting by Dr. Hideo Takahira of the National Nutrition Research Institute. To prepare, K.E. quickly acquired books on fasting and dietary therapy. This was his introduction to the "brown rice, fish, and vegetable diet" and fasting.

K.E. joined the "Kyoto University Hunger Strike Support Group," which included nurses who monitored the students’ vital signs (blood pressure, pulse, respiration, and temperature) daily. K.E. received daily reports on these metrics, along with urine analyses, and occasionally visited the protest site. The hunger strike began on May 12, 1984, and continued until K.E. called a doctor’s stop on the 22nd day, June 3, due to the students’ physical limits. The lead student (Student A), who had been camping outside Takashimaya at Shijo-Kawaramachi in Kyoto, was transported to Takao Hospital on a stretcher to recover.

Student A appeared emaciated after losing 15 kg, standing at 169 cm and weighing 48 kg, but maintained lively affect and independent mobility. Initial health concerns were unsubstantiated. Student A reported that his first post-fast meal, a bowl of rice gruel, was exceptionally palatable. By the following day, he could ambulate slowly without assistance, indicating steady recovery. He noted, “The taste of food is markedly enhanced, and I experience a profound sense of physical rejuvenation.” Motivated by Student A’s experience, K.E. initiated a fasting protocol for himself. From August 8th to the 10th, K.E. progressively reduced caloric intake incrementally daily to 1200 kcal/day, 770 kcal/day, and 330 kcal/day. From August 11th to the 13th, K.E. began a complete water fast, consuming zero calories and zero sodium. On days one and two of the fast, K.E. reported morning dizziness and weakness, which largely resolved by day three. Notably, despite a blood glucose level of 35 mg/dl, K.E. maintained the ability to perform outpatient consultations. Elevated blood ketone levels were likely providing an alternative energy substrate for brain metabolism. During the fast, K.E. lost any sense of hunger pains but desired to consume food and even imagined food in great detail, even causing him to salivate. K.E. lost 4 kg, resulting in a weight of 47 kg at 167 cm, with a 5 cm reduction in waist circumference to 60 cm.

Post-fast, K.E. adhered to a low-calorie diet of approximately 1200 kcal/day. Sleep requirements decreased from 9 to 7 hours per night, with consistent waking at 6 a.m. K.E. became more active with this extra time, incorporating daily hour-long walks with his dog to the hills behind Hirosawa Pond, followed by jogging. Following a series of fasting episodes, K.E. experienced several challenges. He developed an increased preoccupation with food, often consuming any available food. He was frequently recommended comprehensive medical evaluation due to his gaunt appearance. K.E. repeatedly clarified the nature of his fasting regimen to address these concerns for more than one month.

K.E. was 34 when he began an annual fasting practice for several years. Although K.E. initially undertook a water-only fast, subsequent fasts were less restrictive, incorporating clear soup, fruit juice, or rice gruel. Post-fasting, K.E.'s allergic rhinitis was generally well-managed, except during periods of heavy alcohol consumption (e.g., year-end social events) or travel to regions with diets high in sugar, monosodium glutamate, and alcohol (e.g., China). During these episodes, K.E. required treatment with the Chinese herbal medicine Shoseiryuto to control rhinitis symptoms.

K.E. stopped fasting in the same manner after about a dozen fasts. However, he maintained an intermittent fasting routine of two meals per day (skipping breakfast) following his first fast at age 34, and carefully consumed a brown rice, fish, and vegetable diet. K.E. felt fine after a clear soup fast in August 1991, during which β-hydroxybutyrate was measured at 3,507 μmol/L and fasting blood sugar was 52 mg/dL. In 2002, at age 52, K.E. developed diabetes and has since followed an LCD. This diet eliminated postprandial hyperglycemia and large blood sugar fluctuations, mimics the effects of fasting, and renders fasting redundant.

Intermittent fasting may be a more tolerable and effective strategy for weight management than traditional daily calorie restriction, potentially due to its structured yet flexible approach. A clinical trial published in the Annals of Internal Medicine demonstrated that a 4:3 intermittent fasting regimen, involving 80% calorie restriction on three nonconsecutive days per week with normal eating on other days, outperformed daily calorie restriction for weight loss. Over 12 months, participants in the fasting group lost an average of 7.6% of their body weight, compared to 5% in the calorie-cutting group, with better adherence and a higher likelihood of achieving clinically significant weight loss (≥5% of body weight) [1].

Recent studies further highlight the critical role of ketone bodies as an energy source and the efficacy of LCDs as a similar or complementary strategy to fasting. LCDs shift metabolism from glucose dependence to ketone bodies as a primary energy source, offering benefits for managing diabetes and obesity [2]. Furthermore, elevated ketone bodies in patients following LCDs, contributing to metabolic stabilization and weight loss [3]. These findings suggest that ketone bodies serve as an energy substrate for the brain and other tissues, promoting metabolic adaptation during low-glucose states.

Recent evidence further supports the efficacy of LCDs as a similar or complementary strategy to fasting. We reviewed solid evidence showing that LCDs significantly reduce HbA1c, triglycerides, and body weight in type 2 diabetes (T2D) patients, with a 2023 study indicating lower mortality in newly diagnosed T2D cases on LCDs compared to higher-carb diets [4]. A case showed a 61-year-old female with T2D on a super-LCD (12% carbohydrate) reducing HbA1c from 10.5% to 6.6% in 4 months, with ketone bodies at 3081 μmol/L [5]. These findings suggest LCDs can mimick the metabolic benefits of fasting, stabilizing glucose via ketosis, and reduce cardiovascular risks. The ketogenic diet has beneficial effects in clinical applications and is promising for managing diabetes and neurological disorders [6].

A case study of a former professional boxer showed remarkable weight loss and metabolic improvements. A 52-year-old male, previously obese at 85 kg, lost 20 kg over one year by adhering to a super-LCD combined with adequate water intake. This intervention reduced HbA1c from 6.5% to 5.7%, improved HDL cholesterol, and lowered triglycerides, with ketosis playing a central role in metabolic stabilization [7]. Ketone bodies are indispensable to human survival, with ketosis playing a critical role in energy supply and metabolic health maintenance [8].

Figure 1: Relationship between Fasting and LCD.

George Cahill, a Harvard researcher studying ketone bodies in 2006, explains that the brain favors ketones for energy. He notes that while research suggests the brain can function on ketones alone without glucose, proving this is challenging due to experimental and ethical limitations [9]. A 1972 study by Drenick et al., investigated the adaptation of fasting obese men to insulin-induced hypoglycemia, revealing that prolonged fasting (minimum 60 days) significantly alters catecholamine production and glucose metabolism. Before fasting, insulin tolerance tests (0.1–0.2 U/kg) caused hypoglycemic reactions with a significant rise in urinary catecholamine excretion (55 to 107 µg/24 hr, P < 0.01), correlating with a glucose nadir (r = 0.854). After fasting, despite similar glucose declines (nadir 0.5 mmoles/liter), no hypoglycemic reactions or significant catecholamine increases occurred (56 to 81 µg/24 hr, P > 0.1), attributed to enhanced cerebral uptake of ketones (β-OHB A-V difference rising from 0.21 to 0.70 mmoles/liter) replacing glucose as a brain fuel, thus reducing catecholamine response. This adaptation was accompanied by a mean weight loss of 73 lb. The findings suggest that fasting-induced ketosis mitigates the adrenergic response to hypoglycemia, potentially offering clinical benefits for conditions like brittle diabetes or epilepsy [10]. LCDs are a viable alternative to fasting avoiding symptoms of hypoglycemia. In April 2019, the American Diabetes Association’s Consensus Recommendation stated, “The low-carbohydrate diet is one of the most studied dietary therapies” and strongly endorsed it [11]. This stance was reiterated in the 2020 to 2025 guidelines.

Furthermore, three subjects with a genetic defect in glucokinase, causing hyperinsulinemic hypoglycemia and experiencing drug-resistant treatment, showed improvement in hypoglycemic symptoms, including substantial IQ increases, after initiating a ketogenic diet [12]. The risk of hypoglycemia in patients with T2D is lowered, primarily through reduced reliance on glucose-lowering medications, such as insulin and sulfonylureas, which are associated with hypoglycemic events. A meta-analysis found that LCDs significantly reduced medication use and glucose variability, with no evidence of increased hypoglycemia risk compared to control diets, as mild hypoglycemic events were rare and not significantly different between groups. Additionally, the induction of ketosis may further mitigate hypoglycemic symptoms by providing ketones as an alternative brain energy source, stabilizing brain metabolism during low-glucose states [13].

In conclusion, Takao Hospital’s pioneering adoption of a “brown rice, fish, and vegetable diet” in 1984 and an LCD in 1999 has demonstrated significant benefits for managing atopic dermatitis and diabetes. The author’s (K.E.) experiences with fasting, inspired by a 1984 hunger strike, revealed profound metabolic adaptations, including weight loss, enhanced sensory perception, and reduced sleep needs, likely driven by ketone bodies sustaining brain function at low blood glucose levels. Ketone bodies are indispensable for energy supply, and ketosis induced by LCDs or fasting plays a critical role in diabetes management and hypoglycemia mitigation [2, 8]. Clinical evidence supports intermittent fasting, particularly the 4:3 regimen, as more effective than daily calorie restriction for weight loss, achieving 7.6% versus 5% body weight reduction. Both fasting and LCDs stabilize metabolism via ketosis, mitigating hypoglycemia, improving diabetes control, and reducing medication reliance. These strategies enhance metabolic health and reduce cardiovascular risks by leveraging ketone bodies as an alternative energy source [2,3,6]. The therapeutic potential of fasting and LCDs in medical nutrition therapy is impressive, offering structured, tolerable, and effective strategies for weight management and metabolic health.

Conflict of Interest: The authors declare no conflict of interest.

Funding: There was no funding received for this paper.

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