16/8 intermittent fasting and inflammation have become a growing focus of clinical research, with many people exploring whether restricting eating to an eight-hour daily window can help reduce chronic, low-grade inflammation linked to conditions such as type 2 diabetes and cardiovascular disease. During the sixteen-hour fasting period, the body undergoes metabolic shifts that may influence key inflammatory signalling pathways and biomarkers, including C-reactive protein (CRP) and interleukin-6 (IL-6). This article examines the current scientific evidence, relevant NHS and NICE guidance, practical safety considerations, and how to start 16/8 fasting responsibly in the UK.

How 16/8 Intermittent Fasting Affects Inflammation in the Body

16/8 fasting triggers metabolic changes — including falling insulin levels and increased fat oxidation — that may reduce pro-inflammatory cytokine signalling, though direct evidence in free-living adults remains limited and effects are often modest.

The 16/8 method of intermittent fasting involves restricting food intake to an eight-hour window each day, followed by a sixteen-hour fasting period. This pattern has attracted considerable scientific interest, particularly regarding its potential to modulate the body's inflammatory response — a key driver of many chronic diseases.

During the fasting window, the body undergoes several metabolic shifts. Insulin levels fall, glycogen stores are gradually depleted, and the body begins to rely more heavily on fat oxidation for energy. These metabolic changes are thought to influence inflammatory signalling pathways, including the NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) pathway, which plays a central role in regulating the production of pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α).^[1] It is important to note, however, that much of this mechanistic evidence comes from preclinical studies or short-term human trials; direct confirmation in free-living adults following a standard 16/8 pattern remains limited.

Fasting has also been associated in laboratory and animal studies with a cellular housekeeping process known as autophagy — the body's mechanism for clearing damaged cells and proteins. Autophagy has been linked to reduced inflammatory signalling, but whether a typical 16-hour fast reliably induces meaningful autophagy in humans is uncertain and remains an active area of research.^[2]

Where anti-inflammatory effects have been observed in human studies, they are often modest and may be substantially mediated through weight loss and improved metabolic health, rather than fasting timing alone. Inflammation itself is not inherently harmful — acute inflammation is a vital immune response. The concern lies with chronic, low-grade inflammation, which has been linked to conditions including type 2 diabetes, cardiovascular disease, and certain autoimmune disorders. The 16/8 approach may help address this persistent inflammatory state, but the evidence should be interpreted with appropriate caution.

The Science Behind Fasting and Inflammatory Markers

Some randomised controlled trials report small but statistically significant reductions in CRP and IL-6 with time-restricted eating, though these effects may largely reflect caloric restriction and weight loss rather than fasting timing itself.

A growing body of clinical research has examined how intermittent fasting influences measurable inflammatory biomarkers. Key markers studied include C-reactive protein (CRP), interleukin-6 (IL-6), and TNF-α — all of which are used in clinical practice to assess systemic inflammation. CRP in particular is a well-established marker of low-grade chronic inflammation and is routinely measured in NHS settings. White blood cell count, whilst a general indicator of immune activity, is not a sensitive or specific marker for the type of chronic low-grade inflammation relevant to lifestyle interventions and is less commonly used in this context.

Some randomised controlled trials and systematic reviews have reported modest reductions in CRP and IL-6 following periods of intermittent fasting, including time-restricted eating approaches. A 2020 review published in Nutrients found that time-restricted eating was associated with small but statistically significant reductions in CRP, particularly in individuals with overweight or obesity.^[3] These findings suggest that anti-inflammatory effects may be partly — or largely — mediated through weight loss, as adipose tissue is itself a source of pro-inflammatory cytokines.^[15]

However, the evidence is not uniformly positive. A notable randomised controlled trial published in JAMA Internal Medicine in 2020 (Lowe et al.) found that time-restricted eating in adults with overweight did not produce significantly greater weight loss or metabolic improvements compared with unrestricted eating when overall calorie intake was similar. This highlights the importance of distinguishing between effects attributable to caloric restriction and those specific to the fasting pattern itself.

Some researchers propose that eating in alignment with daylight hours — as the 16/8 model can encourage — may support more regulated inflammatory responses through circadian rhythm-linked immune processes. This is a plausible hypothesis supported by small, short-term studies, but its definitive clinical relevance has not yet been established.

The evidence, whilst promising, remains preliminary in several areas. Many studies are short-term, involve small sample sizes, or lack adequate control groups. Effect sizes where reported are generally modest. Larger, longer-duration trials are needed before definitive clinical recommendations can be made. Nonetheless, the current data provides a reasonable scientific rationale for exploring 16/8 fasting as part of a broader anti-inflammatory lifestyle strategy.

Potential Benefits for Chronic Inflammatory Conditions

16/8 fasting may offer complementary benefits in conditions such as type 2 diabetes, cardiovascular disease, and NAFLD, primarily through supporting weight loss and improving metabolic health, but it is not a standalone treatment for any inflammatory condition.

Given the mechanistic and clinical evidence outlined above, researchers have begun investigating whether 16/8 intermittent fasting may offer benefits for individuals living with chronic inflammatory conditions. These include:

• Type 2 diabetes and insulin resistance — Fasting has been shown in some studies to improve insulin sensitivity, which in turn may reduce the chronic low-grade inflammation associated with metabolic dysfunction. People with type 2 diabetes managed with insulin or sulphonylureas should seek GP advice before fasting, in line with NICE NG28 guidance on type 2 diabetes management.^[5][17]

• Cardiovascular disease — Reductions in inflammatory markers such as CRP and improvements in lipid profiles have been observed in some fasting studies, potentially contributing to cardiovascular risk reduction, though evidence remains inconsistent.

• Non-alcoholic fatty liver disease (NAFLD) — NICE guideline NG49 highlights that weight loss of 5–10% can meaningfully improve hepatic outcomes in NAFLD.^[6] Time-restricted eating may support this by helping individuals maintain an energy deficit; however, direct evidence that fasting reduces hepatic inflammation independently of weight loss is limited.

• Inflammatory bowel conditions — Evidence in conditions such as Crohn's disease and ulcerative colitis is very limited and largely anecdotal. Fasting during active disease flares or in individuals who are undernourished is not appropriate and may be harmful. Anyone with an inflammatory bowel condition should discuss dietary changes with their IBD specialist team before making any changes.

For individuals with obesity, intermittent fasting may offer a dual benefit: reducing body fat (itself a source of inflammatory mediators) whilst potentially modulating inflammatory pathways through fasting-related mechanisms. A 2018 study in Nutrition and Healthy Aging (Gabel et al.) examining an 8-hour time-restricted eating protocol in adults with obesity reported reductions in body weight, blood pressure, and atherosclerotic risk. A separate 2018 early time-restricted feeding trial in Cell Metabolism (Sutton et al.) demonstrated improvements in blood pressure, oxidative stress markers, and insulin sensitivity in men with prediabetes, even without weight loss — suggesting some metabolic benefits may be independent of caloric restriction.

It must be emphasised that intermittent fasting should not be considered a standalone treatment for any diagnosed inflammatory condition. It is best viewed as a complementary lifestyle intervention, ideally discussed with a GP or registered dietitian before implementation, particularly for those already receiving medical treatment.

Who Should Exercise Caution With Intermittent Fasting

People with diabetes managed with insulin or sulphonylureas, a history of eating disorders, pregnancy, frailty, or chronic kidney disease should seek GP advice before starting 16/8 fasting due to risks including hypoglycaemia and medication timing issues.

Whilst 16/8 intermittent fasting is generally considered safe for healthy adults, certain groups should approach it with caution or avoid it altogether without medical supervision. Understanding these contraindications is essential for patient safety.

Groups who should seek GP advice before starting:

• Individuals with type 1 or type 2 diabetes managed with insulin or sulphonylureas, due to the risk of hypoglycaemia during fasting periods (see the NHS guidance on hypoglycaemia for further information)

• Those with a history of eating disorders, including anorexia nervosa or bulimia, as restrictive eating patterns may trigger relapse

• Pregnant or breastfeeding women, for whom adequate and consistent nutritional intake is critical

• People with chronic kidney disease or other conditions requiring carefully timed medication or specific dietary management

• Individuals who are underweight or have nutritional deficiencies

• Children and adolescents, for whom fasting is generally unsuitable without specialist oversight

• Older adults and those living with frailty, for whom prolonged fasting may contribute to muscle mass loss (sarcopenia) and increase falls risk — particularly relevant given the NHS focus on falls prevention and maintaining functional independence

There is also the important question of medication timing. The requirement to take medicines with food varies by individual medicine. For example, metformin is generally recommended to be taken with or after meals to reduce gastrointestinal side effects, whilst many statins (such as atorvastatin) and antihypertensives can be taken with or without food.^[9][10] Before altering meal timing, patients should check the Patient Information Leaflet supplied with their medicine, consult the electronic Medicines Compendium (EMC) SmPC, or speak with their pharmacist or GP. Do not assume that all medicines require food.

If you are taking any prescribed medicine and are considering intermittent fasting, always discuss this with your pharmacist or GP first to ensure your medication schedule remains safe and effective.

If at any point during fasting an individual experiences dizziness, fainting, severe headaches, palpitations, or significant mood disturbance, they should stop fasting and contact their GP or call NHS 111 for urgent advice. In the event of collapse, severe chest pain, or new confusion, call 999 immediately. These symptoms may indicate hypoglycaemia, dehydration, or another underlying issue requiring prompt assessment.

If you suspect that a medicine is causing side effects, report this to the MHRA Yellow Card scheme (available at yellowcard.mhra.gov.uk), which monitors the safety of medicines and medical devices in the UK.

NHS and NICE Guidance on Dietary Approaches to Inflammation

NICE and the NHS do not currently endorse intermittent fasting as a treatment for inflammation; the Mediterranean diet has a stronger evidence base, and dietary changes for inflammatory conditions should be discussed with a specialist or registered dietitian.

At present, neither the NHS nor NICE (National Institute for Health and Care Excellence) has issued specific clinical guidelines endorsing intermittent fasting as a treatment for inflammation or inflammatory conditions. However, both bodies provide relevant guidance on dietary approaches to chronic disease management that contextualises the role of fasting.

NICE guidance on weight management — including NICE NG7 (Weight management: lifestyle services for overweight or obese adults) and the current obesity management guideline — acknowledges that a range of dietary approaches, including calorie restriction and total diet replacement, can be effective for weight loss, which in turn reduces inflammatory burden.^[11][12] Whilst intermittent fasting is not explicitly recommended as a first-line intervention, it is not contraindicated, and clinicians are encouraged to support patient-led dietary choices that are safe and sustainable. Patients are advised to check the NICE website (nice.org.uk) for the most current guideline versions and identifiers.

The NHS Eatwell Guide continues to form the foundation of dietary advice in the UK, emphasising a balanced diet rich in fruits, vegetables, wholegrains, and healthy fats — all of which have established anti-inflammatory properties. An anti-inflammatory dietary pattern, such as the Mediterranean diet, has a stronger and more consistent evidence base than fasting alone and is broadly consistent with NHS nutritional guidance.^[14]

For individuals with specific inflammatory conditions — such as rheumatoid arthritis or inflammatory bowel disease — NICE recommends that dietary changes be discussed with a specialist or registered dietitian rather than self-managed. The British Dietetic Association (BDA) provides freely accessible, evidence-based Food Fact Sheets on topics including intermittent fasting and anti-inflammatory diets, which patients can access at bda.uk.com.

In the absence of condition-specific NICE guidance on fasting, the safest approach is to integrate 16/8 fasting within a broader, nutritionally balanced lifestyle plan, ideally with professional support.

Practical Tips for Starting 16/8 Fasting Safely in the UK

Start with a 12-hour fast and extend gradually, stay well hydrated, prioritise anti-inflammatory foods such as oily fish and leafy vegetables, and maintain adequate protein intake of at least 0.75 g per kilogram of body weight per day.

For those who have discussed intermittent fasting with their GP or dietitian and received the go-ahead, starting the 16/8 protocol in a gradual, structured way can help minimise side effects and support long-term adherence.

Getting started safely:

• Choose a realistic eating window — Many people find a 10am to 6pm, 11am to 7pm, or 12pm to 8pm window manageable. Where possible, earlier eating windows (aligned with daylight hours) may offer additional metabolic benefit, as suggested by circadian feeding research, though the most important factor is choosing a window that is sustainable for you and avoids habitual late-night eating.

• Transition gradually — Rather than immediately adopting a strict 16-hour fast, consider starting with a 12-hour fast and extending by one hour each week to allow the body to adapt.

• Stay well hydrated — Water, plain herbal teas, and black coffee (without milk or sugar) are generally considered acceptable during the fasting window and help manage hunger and headaches.

• Prioritise nutrient density during the eating window — Focus on anti-inflammatory foods such as oily fish (rich in omega-3 fatty acids), leafy green vegetables, berries, nuts, seeds, and olive oil — all readily available in UK supermarkets and consistent with the NHS Eatwell Guide.

• Maintain adequate protein intake — The UK Reference Nutrient Intake (RNI) for protein is approximately 0.75 g per kilogram of body weight per day for most healthy adults. Older adults, or those restricting overall energy intake, may benefit from a higher intake of around 1.0–1.2 g/kg/day to help preserve muscle mass — unless this is contraindicated by a condition such as advanced chronic kidney disease. Discuss your individual protein needs with a dietitian if you are unsure.

It is also worth keeping a simple food and symptom diary during the first few weeks. This can help identify any adverse effects and provide useful information if a follow-up appointment with a GP or dietitian is needed. The NHS App and other NHS-approved digital tools may assist with tracking — visit the NHS website (nhs.uk) for current recommendations on health apps.

Finally, remember that consistency over time matters more than perfection. Even partial adherence to a time-restricted eating pattern, combined with a balanced diet, may offer meaningful anti-inflammatory benefits when sustained as part of a healthy lifestyle.

Frequently Asked Questions