Vol. I · Updated April 2026 · 🇬🇧 United Kingdom Clinic Profile

OnTrack Weight Loss and Fitness Retreat
London.

4.6★ rating 49 reviews

DetailsAt a glance

Rating ★★★★☆ 4.6 (49 reviews)

Address OnTrack Retreats, Puckrup Ln, Tewkesbury GL20 6EL, UK

Phone +44 800 689 3104

City London, United Kingdom

About this clinicOverview

OnTrack Weight Loss and Fitness Retreat is a supervised fasting clinic located in London, United Kingdom. According to Google, OnTrack Weight Loss and Fitness Retreat has a public rating of 4.6★ based on 49 user reviews. The clinic is listed on FastingFinder, a directory of supervised fasting providers worldwide.

Information may be outdated or inaccurate; always confirm details directly with the clinic before visiting. See our medical disclaimer for health-related considerations.

LocationMap

The short answerWhat you need to know

OnTrack Weight Loss and Fitness Retreat is a fasting retreat actively listed in London, United Kingdom, tracked from public business sources. Therapeutic fasting (3+ consecutive days with minimal or no caloric intake) sits at the intersection of wellness and clinical medicine. There is no internationally-recognised "fasting practitioner" certification; quality varies enormously across retreats — from medically-supervised programs (Buchinger Wilhelmi in Germany, TrueNorth in California) to wellness-only operations with no on-site medical staff. Public reviews aggregate 4.6★ across 49 ratings, a moderate but consistent signal. Before booking any fast longer than 72 hours, confirm: (1) a medical doctor is on site daily; (2) the protocol has a documented clinical lineage; (3) refeeding is staged and supervised. Therapeutic fasting is contraindicated in pregnancy, type 1 diabetes, eating-disorder history, advanced kidney or liver disease, and during many prescription medications (particularly antihypertensives and antidiabetics, which often require dose adjustment).

Trust ScoreHow we read this listing

67/100

Public data signals — non-clinical

See breakdown

Verification		40
Activity		60
Transparency		85
Engagement		82
Conflict		100

Computed from public business signals only — not a clinical assessment. See our methodology for how each dimension is measured.

Before your visitPractical logistics

Pre-fasting preparation

Reputable fasting clinics require 3–7 days of preparation diet before arrival (reduced protein, no alcohol, no caffeine, gradually smaller meals). This is not optional — it avoids the “refeeding headache” and nausea of a cold-start fast.

Medical intake at admission

Expect blood tests, blood pressure check, and a full health history review. Serious clinics decline clients whose health profile does not fit their program. A clinic that admits everyone without screening is a warning sign.

What to pack

Loose warm clothing (you may feel cold during the fast), walking shoes, a reusable water bottle, your regular medications (show the medical staff on arrival), a journal or book. Skip digital devices — most clinics discourage them.

Daily schedule to expect

Morning: vitals check, light movement (walking, stretching). Midday: broth or herbal tea. Afternoon: rest, group activity, optional treatments. Evening: reflection, sleep. Do not expect to work, train, or multitask — the program is a full retreat.

Breaking the fast

The refeeding phase is as important as the fast itself. Expect 3–7 days of gradual reintroduction: broths, then cooked vegetables, then grains, then proteins. Breaking a fast with a normal meal causes serious GI distress and sometimes electrolyte imbalance.

After you go home

Continue the refeeding protocol strictly for the recommended period. Most of the visible benefits come from this phase, not the fast itself. Plan a quieter week post-retreat — expect fatigue, mood shifts, and renewed hunger.

Questions nobody asksHonest answers

How bad is the hunger really?

Days 1–3 are the hardest. The hunger peaks around day 2, then drops sharply as ketone production stabilizes. By day 4–5 most fasters report minimal hunger and surprisingly clear thinking. This pattern is documented in supervised fasting literature. (Source: PubMed on fasting metabolism.)

Will I lose muscle?

Yes, some — but less than expected. During prolonged fasting, the body preferentially burns fat; muscle protein breakdown is slowed by growth hormone elevation. Short-term muscle loss (3–7 day fasts) is typically 1–2 kg and largely recovered within weeks of resuming normal eating.

Will I have bad breath?

Yes. Ketone production creates acetone, which is exhaled — this is “keto breath”. It is harmless, noticeable around day 2–3, and fades with rehydration. Sugar-free mints and tongue scraping help.

Will my period stop?

Possibly, for prolonged fasts (over 5–7 days) in women with low body weight. The cycle typically resumes within 1–3 months of normal eating. If you have a history of amenorrhea (absent periods) or low body weight, a prolonged fast is not appropriate — consult your physician.

Can I shower, walk, and move around?

Yes. Most clinics encourage gentle movement (walking, stretching, light yoga). Daily showers are standard. What is discouraged: intense exercise, saunas, cold plunges in the first days — the body is in an energy-conservation state.

Why not do it at home?

Supervised fasting manages risks that home fasting does not: electrolyte monitoring, blood pressure tracking, safe refeeding protocols, and medical staff for the rare complications (refeeding syndrome, gallbladder events, arrhythmias). If you have any health condition, home prolonged fasting is not appropriate.

Will the weight stay off?

The visible weight loss during the fast is mostly water and glycogen — most of it returns within 7–14 days of refeeding. Actual fat loss is typically 30–50% of the total weight lost. For sustained fat loss, the fast must be followed by lifestyle changes, not a return to prior habits.

Can I continue my regular medications?

Some yes, some no, some require dose adjustment during the fast. This is why a medically supervised clinic is essential — they review all medications at intake and adjust with your prescribing physician.

How is fasting safely managed for people with Type 1 or Type 2 diabetes?

Fasting protocols for diabetic patients require careful medical supervision. For Type 1 diabetes, prolonged fasting is generally not recommended without intensive endocrinologist supervision due to risks of hypoglycemia, ketoacidosis, and insulin pump adjustment complexity. For Type 2 diabetes, intermittent fasting and time-restricted eating have shown promising results in clinical research (NCT05698654 and similar trials), but medication adjustment (especially insulin, sulfonylureas) is essential. Always consult your endocrinologist before starting any fasting protocol — most reputable fasting clinics screen for diabetes during intake and coordinate with the patient's medical team.

Is fasting appropriate for people with a history of eating disorders?

Most clinical guidelines recommend extreme caution. People with a personal history of anorexia, bulimia, or binge eating disorder typically should not pursue prolonged fasting without specialised psychiatric and medical supervision. The structure of fasting can trigger disordered eating patterns. For people with a history of eating disorders, registered dietitians and eating disorder specialists generally recommend regular balanced eating rather than fasting protocols. Reputable fasting clinics screen for eating disorder history during intake and may decline patients based on clinical assessment.

How are medications managed during a multi-day fast?

Most reputable fasting clinics conduct comprehensive medication reviews during intake, coordinating with the patient's prescribing physicians. Some medications continue safely (many cardiovascular drugs, thyroid medication). Some require dose adjustment (blood sugar medications, blood pressure medications that can cause hypotension during fasting). Some are paused (NSAIDs that irritate empty stomach lining, sleep aids). Some are contraindicated (certain psychiatric medications requiring food intake). Never adjust prescription medications independently — always coordinate with both your prescribing physician and the fasting clinic.

What is electrolyte management during prolonged fasting and why is it critical?

Electrolyte balance — particularly sodium, potassium, magnesium — becomes critical during prolonged water fasting (3+ days). The body's electrolyte losses through urine continue while intake is limited, creating risks for cardiac arrhythmia, muscle weakness, and confusion. Most medical fasting protocols include electrolyte monitoring and supplementation (Himalayan salt, electrolyte powders, mineral broths during modified fasts). Reputable clinics include regular blood electrolyte tests during multi-day fasts. The Buchinger Wilhelmi protocol, for example, includes daily electrolyte assessment.

What is refeeding syndrome and how is it prevented after a prolonged fast?

Refeeding syndrome is a serious medical condition that can occur when food is reintroduced rapidly after extended fasting (5+ days), causing sudden electrolyte and fluid shifts that can affect cardiac and neurological function. Most clinical fasting protocols include carefully structured refeeding phases: typically starting with small portions of easily digestible foods (broths, fruit juices, soft fruits) over 1-3 days proportional to fast length, gradually increasing complexity. Medical supervision during refeeding is as important as during the fast itself. Reputable clinics never discharge patients without proper refeeding.

When is medical supervision required versus optional for fasting protocols?

Most clinical guidelines suggest medical supervision is required for: fasts longer than 5 days, fasts in people with any chronic medical condition (diabetes, cardiovascular disease, kidney disease), fasts in people taking prescription medications, fasts in elderly (65+) or underweight individuals, fasts in pregnant or breastfeeding women (typically contraindicated). Optional but recommended for: first-time fasters trying 24-72 hour protocols, fasts during high physical activity periods, fasts combined with other significant dietary changes. Intermittent fasting (16:8, 5:2) is generally considered safe for healthy adults without supervision.

What is the Buchinger method and why has it gained renewed interest in 2025-2026?

The Buchinger method is a medically supervised therapeutic fasting protocol developed by Dr. Otto Buchinger in Germany, celebrating its 100-year anniversary in 2025. It typically involves 5-21 day fasts at clinical centres (Buchinger Wilhelmi clinics in Germany and Spain are the most renowned), combining water and herbal teas, vegetable broths, and small amounts of honey or juice. The protocol includes daily medical monitoring, gentle movement, and supportive treatments. Renewed interest in 2025-2026 reflects the longevity and metabolic health wellness trend, with published research on cardiovascular markers, inflammation, and autophagy supporting the approach (Stange et al. and ongoing Buchinger Wilhelmi clinical publications).

What is the Fasting Mimicking Diet (FMD) and how does it differ from water fasting?

The Fasting Mimicking Diet (FMD) was developed by Dr. Valter Longo's lab at USC and commercialised primarily as ProLon (5-day at-home protocol). FMD provides specific low-calorie (around 700-1100 cal/day), low-protein, low-carb meal kits designed to trigger fasting-like metabolic effects (autophagy, cellular regeneration) while providing some nutrition. Gained mainstream attention in 2025-2026 (Fortune, Daily Beast coverage, celebrity endorsements). Different from water fasting in tolerability and at-home applicability. Clinical research from Longo lab supports specific health markers; protocol is typically done 1-3 times per year.

What is autophagy and what does research say about fasting's role in activating it?

Autophagy is the cellular process where damaged components are broken down and recycled, recognised as fundamental to cellular health (Yoshinori Ohsumi received the 2016 Nobel Prize for autophagy research). Animal studies and limited human research suggest fasting may activate autophagy more strongly than caloric restriction alone, with effects appearing after 16-24 hours of fasting and increasing over longer periods. The exact protocols and optimal duration for autophagy benefits in humans remain active research areas (NCBI Mizushima reviews, ongoing clinical trials). Many fasting practitioners cite autophagy as a key mechanism for fasting's longevity benefits.

How does fasting fit into the longevity wellness movement of 2025-2026?

Fasting has become a central practice in the longevity wellness movement, identified as one of the most accessible interventions associated with extended healthspan in current research (PureWow longevity coverage 2026, ongoing clinical trials at USC, Stanford, Harvard). Practitioners often combine intermittent fasting (16:8 daily) with periodic prolonged fasts (3-7 day quarterly) and seasonal cleanses. Major longevity research figures (Peter Attia, Valter Longo, David Sinclair) discuss fasting protocols in their published work. The movement is contributing to mainstream acceptance and ongoing research investment.

What does current research say about fasting and weight loss versus metabolic health?

Clinical research distinguishes between weight loss effects (relatively short-term, typically regained without sustained lifestyle changes) and metabolic health effects (improved insulin sensitivity, lipid profiles, blood pressure markers — often persisting even with some weight regain). Studies on intermittent fasting (de Cabo & Mattson NEJM 2019) suggest metabolic benefits may be independent of weight loss. For sustainable weight management, most clinical guidelines support fasting as one tool combined with overall dietary pattern improvements, regular activity, and stress management — not as a standalone solution.

Is fasting a sustainable long-term practice or a periodic intervention?

Most clinical research and practitioner experience suggests fasting works best as a periodic intervention rather than continuous restriction. Intermittent fasting (16:8 daily) can be sustained long-term by many people. Prolonged fasts (3-7 days) are typically done 1-4 times per year. Multi-week clinical fasts (Buchinger 14-21 days) are typically annual or biannual. Daily very low calorie restriction long-term is generally not recommended due to metabolic adaptation and nutritional concerns. The 2025-2026 trend emphasises periodic strategic fasting integrated with overall healthy nutrition rather than chronic restriction.

What research exists on fasting for specific medical conditions beyond general wellness?

Active clinical research areas include: fasting and Type 2 diabetes management (multiple trials showing glycemic improvements), fasting and cardiovascular disease markers, fasting and cancer treatment support (USC research on chemotherapy tolerability — Fortune coverage), fasting and neurological conditions (Alzheimer's prevention research), fasting and autoimmune conditions (immune system reset hypothesis). Results are promising but most applications require medical supervision and individualised protocols. The Buchinger Wilhelmi clinics have decades of published clinical data on specific condition outcomes.

How does fasting interact with mental health considerations?

Fasting can have varied mental health effects requiring careful consideration. Many people report improved mental clarity, mood stability, and reduced anxiety during fasting. However, fasting can also trigger or worsen anxiety, depression, irritability, and (as noted above) disordered eating patterns in vulnerable individuals. The structure of clinical fasts at supervised facilities (Buchinger, similar centres) typically include psychological support and group dynamics that benefit mental wellbeing. People with active mental health conditions should consult their mental health provider before starting fasting protocols.

How does normal hunger during fasting compare to concerning symptoms requiring attention?

Normal fasting hunger typically: comes in waves (peaks around regular meal times then subsides), is accompanied by mild fatigue or irritability, decreases significantly after day 2-3 in prolonged fasts. Concerning symptoms requiring attention: severe headache persisting beyond first 24-48 hours, dizziness on standing, rapid or irregular heartbeat, muscle cramping, confusion, extreme weakness, fainting. Most reputable fasting clinics include 24-hour medical contact and clear guidelines on when to break a fast. Self-directed fasters should know symptoms requiring immediate medical attention.

What can people drink during different types of fasting protocols?

Permitted beverages vary by protocol. Water fasting: pure water only (sometimes salt water for electrolytes). Buchinger-style modified fast: water, herbal teas, vegetable broths, small amounts of fruit juice (~250 ml/day) and honey. Intermittent fasting (16:8): water, black coffee, plain tea during fasting window; some protocols allow small amounts of cream or coconut oil. Bone broth fasting: clear broths and water. Fasting Mimicking Diet (ProLon): specific provided meal kits plus water. Generally avoided during fasts: artificial sweeteners (may trigger insulin response in some individuals), alcohol, sugary drinks, caloric beverages.

Who should wait or get cleared firstContraindications

Absolute contraindications

Pregnancy or breastfeeding, type 1 diabetes, history of amenorrhea or low body weight, severe heart disease, kidney disease, liver failure, active cancer treatment, terminal illness. Prolonged fasting in these conditions is dangerous.

Medical history requiring physician approval

Type 2 diabetes (medication adjustments needed), gallstones (refeeding can trigger attack), history of eating behaviour concerns (consult your physician before any prolonged fasting protocol), cardiovascular disease, hypertension on medication.

Age considerations

Under 18: not appropriate. Over 65: case-by-case with physician clearance and adjusted protocol (typically shorter fasts, closer monitoring).

Legal and regulatory

Fasting clinics are regulated differently by country. Some jurisdictions restrict prolonged fasting programs (France, Morocco, Switzerland). Check the clinic's licensing before booking internationally.

Disclaimer

This list is informational and not exhaustive. Consult a licensed healthcare professional who knows your medical history before any fasting protocol. See our medical disclaimer.

Red flags before you bookStudio quality signals

No medical intake or blood work

Any serious fasting clinic runs blood tests and medical history before admission. A clinic that admits anyone without a health check is operating recklessly.

No on-site medical supervision

Prolonged fasting has real risks (electrolyte imbalance, cardiovascular events, refeeding syndrome). A clinic without a physician or trained nursing staff on site is not a clinic.

“One size fits all” programs

Real clinics tailor duration and protocol to your health profile. A clinic offering the same 14-day program to everyone is selling a cookie-cutter, not medicine.

Extreme health claims

Claims of curing cancer, diabetes, autoimmune disease, or chronic illness through fasting are not supported by mainstream medical research. Clinics marketing these should be avoided.

No refeeding protocol provided

The refeeding phase is where most complications occur. A clinic that sends you home with “just eat normally” is negligent.

Pushy follow-up sales

Quality clinics do not pressure you into longer programs mid-stay. A clinic pushing you to extend or return immediately is monetizing your vulnerability.

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Frequently asked questionsAbout OnTrack Weight Loss and Fitness Retreat

How do I book an appointment at OnTrack Weight Loss and Fitness Retreat?

To book a session at OnTrack Weight Loss and Fitness Retreat, we recommend contacting +44 800 689 3104 directly. Most supervised fasting clinics offer online booking, email reservations, or phone scheduling. Availability can vary — contacting ahead is always advised.

What should I expect at a first visit to OnTrack Weight Loss and Fitness Retreat?

First-time visitors to a supervised fasting clinic typically arrive 10–15 minutes early for an intake consultation. OnTrack Weight Loss and Fitness Retreat may ask about your health history, goals, and any contraindications. Expect an intake form and a brief conversation before your first session.

How much does a session at OnTrack Weight Loss and Fitness Retreat cost?

Pricing at OnTrack Weight Loss and Fitness Retreat varies by session length, package, and whether it's a first visit, private, or group class. Typical supervised fasting sessions in London range around €1,500 – €8,000. For the current rate card, check with +44 800 689 3104.

Is OnTrack Weight Loss and Fitness Retreat suitable for beginners?

Most supervised fasting clinics, including OnTrack Weight Loss and Fitness Retreat, welcome beginners. A qualified practitioner will adapt the session to your level and any specific health concerns. If you've never tried supervised fasting before, mention it when booking so they can prepare accordingly.

Does OnTrack Weight Loss and Fitness Retreat offer private, group, or gift options?

Many clinics in London offer flexible formats: private one-on-one sessions, duet/group classes, corporate wellness bookings, and gift vouchers. Specific offerings vary — contact +44 800 689 3104 to ask about private sessions, gift cards, package deals, and multi-session memberships.

Services & optionsBeyond standard classes

Private sessions

One-on-one format with a dedicated practitioner, useful for personalized pacing, specific goals, or recovery. Availability varies — ask OnTrack Weight Loss and Fitness Retreat about private rates.

Group & duet classes

Some clinics in the city offer duet (2-person) or small-group formats, often at a reduced per-person rate. Check directly with OnTrack Weight Loss and Fitness Retreat for current schedule and group sizes.

Gift vouchers & cards

Gift vouchers make a practical wellness present and are commonly available at established clinics. Reach out to OnTrack Weight Loss and Fitness Retreat directly to confirm.

Memberships & multi-session packages

Regular practice is typically priced more affordably through 5-class packs, 10-class packs, or monthly memberships. Trial packages for new clients are also common.

Corporate & event bookings

For team-building, corporate wellness events, or private group sessions, many clinics take direct bookings. Mention the size of your party and preferred format when you inquire.

Availability and pricing are set by the clinic and can change. Always confirm before booking.

What to expectA typical supervised fasting session

A supervised fasting session is a specialized wellness experience designed by trained professionals. Duration, pricing, and specific approach vary by practitioner — we recommend contacting the clinic in advance to discuss your goals, any prior experience, and practical details like what to wear and when to arrive.

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OnTrack Weight Loss and Fitness RetreatLondon.

OnTrack Weight Loss and Fitness Retreat
London.