Prolonged starvation as treatment for severe obesity refers to extended periods of total fasting under medical supervision, a practice explored in the mid-20th century but now abandoned due to serious safety concerns. This historical approach involved complete abstention from food for weeks or months, causing rapid weight loss but also life-threatening complications including cardiac arrhythmias, severe electrolyte disturbances, and nutritional deficiencies. The NHS and NICE do not recommend prolonged starvation for obesity management. Current evidence-based guidelines emphasise safer, sustainable interventions including lifestyle modification, very-low-energy diets, pharmacological treatments, and bariatric surgery. Understanding why this extreme approach is no longer considered acceptable medical practice helps patients and healthcare professionals make informed decisions about safe, effective weight management strategies.

What Is Prolonged Starvation Therapy for Severe Obesity?

Prolonged starvation therapy, also known as therapeutic fasting or total fasting, refers to the deliberate abstention from all caloric intake for extended periods—typically ranging from several days to several weeks—under medical supervision. Historically, this approach was explored as a treatment for severe obesity (defined as BMI ≥40 kg/m² or ≥35 kg/m² with significant comorbidities) during the mid-20th century, when understanding of metabolic processes and safer alternatives were limited.

During prolonged fasting, the body undergoes significant metabolic adaptations. After depleting glycogen stores within 24–48 hours, the body shifts to ketogenesis, breaking down fat stores to produce ketone bodies for energy. Whilst this process can result in rapid weight loss, it also triggers protein catabolism, where muscle tissue is broken down to provide amino acids for gluconeogenesis—the production of glucose for organs that require it. Red blood cells, in particular, cannot utilise ketones at all and rely entirely on glucose supplied through gluconeogenesis.

Historic protocols typically permitted water and non-caloric fluids, along with vitamin and mineral supplementation, but provided zero caloric intake from food. This creates substantially greater physiological stress and metabolic consequences than intermittent fasting (which typically involves shorter fasting windows of 16–24 hours with regular eating periods) or very-low-energy diets (VLEDs, providing 800 calories or fewer daily but still including essential nutrients).

This approach is not recommended in UK clinical practice and is not included in NICE or NHS treatment pathways for obesity. Current evidence-based guidelines emphasise safer, sustainable interventions that preserve lean body mass and support long-term behavioural change. Prolonged starvation is contraindicated in pregnancy and breastfeeding, children and young people under 18 years, people with type 1 diabetes, and those with current or previous eating disorders. Understanding the historical context and inherent risks of prolonged starvation is essential for both patients and healthcare professionals when considering weight management strategies.

Historical Use and Medical Supervision Requirements

Prolonged fasting for obesity gained attention in the 1960s and early 1970s, when several medical centres experimented with supervised starvation programmes. The most cited case, reported in the medical literature, involved a Scottish man who fasted for 382 days under medical supervision, losing approximately 125 kg. Such extreme interventions were conducted in inpatient settings with continuous monitoring, as clinicians recognised the substantial risks involved.

Medical supervision during historical fasting protocols typically included:

• Daily clinical assessment and vital signs monitoring

• Regular blood tests to assess electrolyte balance, renal function, and metabolic parameters

• Supplementation with essential vitamins and minerals, particularly thiamine, folate, and potassium

• Continuous ECG monitoring in some cases due to cardiac risks

• Immediate access to emergency medical intervention

Despite these precautions, serious complications occurred, including sudden cardiac death, severe electrolyte disturbances, and hepatic dysfunction. The medical literature from this era documented cases of fatal cardiac arrhythmias, even in patients who appeared clinically stable. These outcomes prompted significant ethical and safety concerns within the medical community.

By the late 1970s, the practice had largely been abandoned in favour of safer approaches. The recognition that rapid weight loss was often followed by weight regain—in some cases substantial—further diminished enthusiasm for this intervention. Additionally, the psychological impact of extreme dietary restriction, including the development of disordered eating patterns, became increasingly apparent.

Today, any consideration of prolonged fasting would require extraordinary justification and would only be contemplated in exceptional circumstances within specialist metabolic units. The stringent supervision requirements and documented risks make this approach incompatible with contemporary patient safety standards and evidence-based medicine principles.

Risks and Complications of Extended Fasting

Prolonged starvation poses numerous serious health risks that can affect multiple organ systems. Understanding these complications is essential for appreciating why this approach is no longer considered acceptable medical practice.

Cardiovascular complications represent the most serious immediate risk. Extended fasting can cause dangerous electrolyte imbalances, particularly hypokalaemia (low potassium), hypomagnesaemia (low magnesium), and hypophosphataemia (low phosphate). These disturbances can trigger potentially fatal cardiac arrhythmias, including ventricular tachycardia and sudden cardiac arrest. The heart muscle itself may be affected, with documented cases of cardiomyopathy and reduced cardiac output. Postural hypotension is common, increasing fall risk.

Metabolic and endocrine effects include severe hypoglycaemia, particularly dangerous for individuals with diabetes. Prolonged fasting disrupts thyroid function, reducing metabolic rate—a counterproductive effect when treating obesity. Hyperuricaemia (elevated uric acid) frequently occurs, potentially precipitating acute gout attacks. Women may experience amenorrhoea (cessation of menstruation), and both sexes can develop reduced bone density with prolonged nutritional deprivation. People taking SGLT2 inhibitors (a class of diabetes medication) face an increased risk of euglycaemic diabetic ketoacidosis during extended fasting and should seek medical advice before any fasting regimen.

Nutritional deficiencies develop rapidly without supplementation. Thiamine (vitamin B1) deficiency can cause Wernicke's encephalopathy, a neurological emergency characterised by confusion, ataxia, and eye movement abnormalities. Deficiencies in other B vitamins, vitamin C, and essential fatty acids can cause various complications ranging from anaemia to impaired wound healing.

Gastrointestinal and hepatobiliary complications include hepatic steatosis (fatty liver), which paradoxically worsens during starvation, and potential progression to hepatic dysfunction. Rapid weight loss significantly increases the risk of gallstone formation and acute cholecystitis. Refeeding after prolonged fasting carries its own serious risks, including refeeding syndrome—a potentially fatal condition characterised by severe electrolyte shifts (particularly hypophosphataemia), fluid imbalance, and organ dysfunction. UK guidance on refeeding syndrome prevention (NICE CG32 and BAPEN guidance) emphasises careful monitoring and thiamine supplementation when reintroducing nutrition after prolonged fasting or malnutrition.

Psychological consequences should not be underestimated. Prolonged fasting can exacerbate or trigger eating disorders, depression, and anxiety. The extreme nature of total food restriction may establish unhealthy relationships with food that persist long after the fasting period ends. Screening for eating disorders should be undertaken before any intensive weight management intervention.

Current NHS Guidelines and Evidence-Based Alternatives

The NHS and NICE do not recommend prolonged starvation as a treatment for obesity. Current evidence-based guidelines emphasise sustainable, multicomponent interventions that address the complex biological, psychological, and social factors contributing to obesity.

NICE guideline CG189 (Obesity: identification, assessment and management) recommends a tiered approach to obesity management:

• Lifestyle interventions form the foundation, combining dietary modification, increased physical activity, and behavioural strategies. These programmes should be delivered over at least 12 weeks and focus on sustainable habit change rather than rapid weight loss.

• Very-low-energy diets (VLEDs) providing 800 calories or fewer daily may be considered as part of a multicomponent weight management strategy for adults with obesity. VLEDs are typically used for a limited duration (usually up to 12 weeks) with careful monitoring, nutritional adequacy, and structured transition planning. Crucially, VLEDs still provide essential nutrients and are delivered within specialist weight management services.

• Pharmacological interventions may be prescribed alongside lifestyle interventions for eligible patients. Orlistat (which reduces fat absorption) may be considered for adults with BMI ≥30 kg/m² (or ≥28 kg/m² with other risk factors). GLP-1 receptor agonists such as semaglutide 2.4 mg (Wegovy) and liraglutide 3.0 mg (Saxenda) are available within NHS specialist weight management services (tier 3 or tier 4) for adults meeting specific eligibility criteria defined in NICE Technology Appraisals. These medications enhance satiety and reduce appetite. Treatment is typically time-limited (usually up to 2 years) and should be discontinued if insufficient weight loss is achieved. Prescribing should follow the relevant Summary of Product Characteristics (SmPC) available via the MHRA or EMC. If you experience a suspected side effect from any weight-loss medicine, report it via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

• Bariatric surgery (gastric bypass, sleeve gastrectomy, or gastric banding) is recommended for adults with BMI ≥40 kg/m², or ≥35 kg/m² with significant obesity-related comorbidities, when other interventions have been unsuccessful. NICE also recommends considering bariatric surgery for adults with recent-onset type 2 diabetes and BMI 30.0–34.9 kg/m². For people with BMI ≥50 kg/m², bariatric surgery may be considered as a first-line option. Surgery offers the most substantial and sustained weight loss for severe obesity.

The NHS Diabetes Prevention Programme and specialist weight management services (organised in tiers 1–4) provide structured support with multidisciplinary teams including dietitians, psychologists, and physicians. These services recognise obesity as a chronic condition requiring long-term management rather than quick fixes.

Evidence consistently demonstrates that gradual weight loss of 0.5–1 kg weekly is more sustainable and safer than rapid weight reduction. Importantly, even modest weight loss of 5–10% can significantly improve metabolic health, reducing risks of type 2 diabetes, cardiovascular disease, and other obesity-related complications.

When Medical Supervision Is Essential for Severe Obesity

Individuals with severe obesity should seek medical supervision when embarking on any weight management programme, particularly if considering intensive interventions. Professional guidance ensures safety, addresses underlying health conditions, and optimises outcomes.

You should contact your GP or specialist weight management service if:

• Your BMI is ≥40 kg/m² or ≥35 kg/m² with obesity-related health conditions such as type 2 diabetes, hypertension, sleep apnoea, or osteoarthritis

• You have previously attempted multiple weight loss programmes without sustained success

• You are considering very-low-energy diets or commercial fasting programmes

• You have existing cardiovascular disease, diabetes, or other chronic conditions that may be affected by dietary changes

• You experience symptoms such as chest pain, severe breathlessness, fainting, or rapid heartbeat during weight loss attempts

Medical supervision for severe obesity typically involves:

• Comprehensive assessment including medical history, physical examination, and baseline investigations (typically full blood count, urea and electrolytes, liver function tests, lipid profile, HbA1c, and thyroid function tests)

• Screening for obesity-related complications, comorbidities, and eating disorders

• Individualised treatment planning considering your preferences, circumstances, and health status

• Regular monitoring of weight, metabolic parameters, and overall health during interventions

• Psychological support to address emotional eating, body image concerns, and motivation

• Coordination with multidisciplinary teams including dietitians, physiotherapists, and mental health professionals

• Referral to NHS tiered weight management services (tiers 1–4) via your GP when appropriate

Seek urgent medical attention by calling 999 or attending A&E if you experience:

• Chest pain, palpitations, or irregular heartbeat

• Severe dizziness, fainting, or confusion

• Persistent vomiting or inability to tolerate fluids

• Severe weakness or muscle cramps

• Visual disturbances or severe headaches

• Collapse or loss of consciousness

For urgent advice that is not life-threatening, contact NHS 111 online or by phone.

Remember that sustainable weight management is a gradual process requiring patience and ongoing support. There are no safe shortcuts to significant weight loss, and any intervention promising rapid results without medical supervision should be approached with extreme caution. Avoid unsupervised fasting, particularly if you are pregnant or breastfeeding, under 18 years of age, have type 1 diabetes, have a current or previous eating disorder, or take SGLT2 inhibitors for diabetes. Your GP can refer you to NHS specialist weight management services where appropriate, ensuring you receive evidence-based care tailored to your individual needs and circumstances.

Frequently Asked Questions