Can you eat yogurt during intermittent fasting? It's one of the most common questions asked by those following popular protocols such as 16:8 or 5:2. The short answer is that yoghurt will break your fast — it contains calories from protein, carbohydrates, and fat that trigger an insulin response. However, understanding when and how to include yoghurt within your eating window can help you maximise its considerable nutritional benefits. This guide covers how fasting works, which yoghurt types are best, and what NHS and dietitian guidance says about dairy within a fasting plan.

How Intermittent Fasting Works and What Breaks a Fast

Intermittent fasting alternates defined fasting and eating periods; any intake above approximately 5–10 kcal — including calories from food or sweetened drinks — is sufficient to break a fast by triggering an insulin response.

Intermittent fasting (IF) is an eating pattern that alternates between defined periods of fasting and eating. Popular protocols include the 16:8 method (fasting for 16 hours, eating within an 8-hour window), the 5:2 approach (normal eating five days per week, with significant calorie restriction on two non-consecutive days), and alternate-day fasting. Rather than dictating what you eat, intermittent fasting focuses primarily on when you eat.

During the fasting period, the aim is to keep insulin levels low and allow the body to draw more on stored fat for energy. It is important to note that routine time-restricted eating — such as a daily 16:8 pattern — does not typically produce sustained nutritional ketosis. Ketosis generally requires either prolonged fasting (usually beyond 24–48 hours) or a very low-carbohydrate diet maintained over time. Consuming calories during the fasting window triggers an insulin response, which interrupts the fat-burning process; this is why what you consume during a fast matters.

Technically, any intake providing more than approximately 5–10 kcal is generally considered sufficient to break a fast. In practice:

• Any food or drink containing meaningful calories (including fats, proteins, and carbohydrates) will break a fast

• Sweetened beverages, including fruit juices and flavoured waters, break a fast

• Milk or cream in tea or coffee: even a small splash adds calories; for strict metabolic fasting this counts, though for weight management goals the practical impact of a very small amount (e.g., a teaspoon of milk) may be minimal

Drinks widely accepted as fasting-compatible include plain water, black coffee, and plain herbal teas, as these contain negligible or no calories. Some practitioners also use zero-calorie sweeteners; these contribute negligible energy, though evidence on their effects on appetite and insulin response is mixed and individualised.

It is worth noting that some people follow stricter interpretations of fasting, whilst others adopt a more flexible approach — particularly when the primary goal is weight management rather than therapeutic fasting. The British Dietetic Association (BDA) and NHS both offer patient-facing guidance on IF and safe practice, which is worth consulting before starting.

Does Eating Yoghurt Break Your Intermittent Fast?

Yes, yoghurt breaks an intermittent fast — even a 100 g serving of plain low-fat yoghurt provides 55–70 kcal, and its protein and lactose content stimulate an insulin response that interrupts the fasted metabolic state.

The straightforward answer is yes — eating yoghurt during your fasting window will break your fast. Yoghurt contains calories derived from protein, carbohydrates (primarily lactose), and fat, all of which stimulate an insulin response. Even a small 100 g serving of plain low-fat yoghurt typically provides around 55–70 kcal (based on UK nutrient composition data, McCance & Widdowson), which is sufficient to interrupt the fasted metabolic state.^[4]

From a biochemical standpoint, the protein content in yoghurt — generally between 4–10 g per 100 g depending on the variety — is particularly relevant. Protein stimulates the release of insulin and other anabolic hormones, which directly counteracts the hormonal environment that intermittent fasting aims to maintain. The natural sugars (lactose) present in yoghurt also contribute to a glycaemic response. The degree of metabolic impact scales with portion size and varies between individuals and yoghurt styles.

Context matters, however. If your primary goal with intermittent fasting is weight management or improved dietary habits rather than strict metabolic fasting or therapeutic purposes (such as managing blood glucose in type 2 diabetes), consuming a small amount of plain, unsweetened yoghurt may have a minimal practical impact on your overall outcomes. For those following IF for more specific health reasons — including insulin sensitivity, gut rest, or as part of a medically supervised plan — it is advisable to reserve yoghurt strictly for the eating window.

If you are uncertain about how strictly to adhere to your fasting protocol, speaking with a registered dietitian or your GP is recommended, particularly if you have an underlying health condition.

Types of Yoghurt and Their Effect on Fasting

Plain Greek yoghurt and skyr are the most suitable choices during the eating window, offering high protein and lower sugar; flavoured yoghurts often contain 10–15 g of added sugars per 100 g and are less appropriate metabolically.

Not all yoghurts are nutritionally equivalent, and understanding the differences can help you make informed choices during your eating window. The main types available in UK supermarkets include:

• Plain full-fat yoghurt: Higher in calories and saturated fat, but lower in added sugars. Contains natural lactose and beneficial fatty acids.

• Plain low-fat or fat-free yoghurt: Reduced calorie content. Plain versions do not typically contain added sugars; however, flavoured low-fat yoghurts often have sugars or sweeteners added to compensate for lost flavour. Always check the nutrition label.

• Greek yoghurt: Strained to remove much of the whey, resulting in a thicker texture and higher protein content (up to 10 g per 100 g). Lactose content is reduced compared with unstrained yoghurt, though this varies by brand. A nutritionally dense option.

• Skyr: An Icelandic-style cultured dairy product with very high protein and low fat, increasingly popular in the UK.

• Flavoured or fruit yoghurts: These typically contain significant added or free sugars — sometimes 10–15 g per 100 g — making them less suitable from a metabolic standpoint.^[4] Note that total sugars on the label include both natural lactose and any added sugars; check the ingredients list for added sugars specifically.

• Plant-based yoghurts (soya, oat, coconut): Nutritional profiles vary considerably. Soya-based yoghurts can offer protein levels comparable to standard dairy yoghurt. Oat- and coconut-based options are typically lower in protein. Many are fortified with calcium, vitamin D, and iodine, but this is not universal — check the label, as iodine in particular is important and not always added.

For those practising intermittent fasting, plain Greek yoghurt or skyr are generally considered the most nutritionally advantageous options during the eating window, owing to their high protein content, lower sugar levels, and potential probiotic benefits. When choosing any yoghurt, check the label for live cultures, added sugars, and fortification with key micronutrients. The NHS Eatwell Guide recommends dairy or fortified dairy alternatives as part of a balanced diet.

When to Include Yoghurt During Your Eating Window

Yoghurt should be eaten exclusively within your eating window; consuming it at the start of the window — such as at breakfast on a 16:8 protocol — can promote satiety and help reduce overall calorie intake.

Since yoghurt breaks a fast, it should be consumed exclusively within your designated eating window. Timing when you eat yoghurt can help you maximise both satiety and nutritional benefit throughout the day.

Consuming yoghurt at the start of your eating window — for example, as a breakfast food when following a 16:8 protocol — can be particularly effective. Its high protein content promotes feelings of fullness, which may help reduce overall calorie intake during the remainder of the eating period. Evidence from nutrition research suggests that higher-protein meals are associated with improved satiety and reduced appetite later in the day, which aligns with the goals of intermittent fasting, though individual responses vary.^[9]

Alternatively, yoghurt can serve as a nutritious snack or light meal component mid-window, paired with:

• Fresh berries or sliced fruit (for added fibre and antioxidants)

• A small handful of nuts or seeds (for healthy fats and additional protein)

• A drizzle of honey, used sparingly — this adds free sugars, so keep portions small

• Wholegrain, lower-sugar granola in modest portions — check labels, as granola can be high in added sugars and calories

For those following the 5:2 protocol, yoghurt can be a practical choice on restricted-calorie days. A 150 g serving of plain low-fat yoghurt provides roughly 80–100 kcal whilst delivering meaningful protein and calcium, making it a filling yet calorie-conscious option.

As a general preference rather than a strict rule, some people find it easier to transition into their fasting window if they avoid eating very close to the cut-off time, as this can make the initial fasting period feel more comfortable — though there is no strong evidence that the timing of your last meal within the eating window significantly affects outcomes.

Health Benefits of Yoghurt Within an Intermittent Fasting Plan

Yoghurt supports gut health via live cultures, provides calcium and protein for bone and muscle maintenance, and may help moderate post-meal blood glucose — making it a nutritionally well-rounded choice within a fasting plan.

Incorporating yoghurt into your eating window can complement the broader health goals associated with intermittent fasting. Yoghurt is a nutrient-dense food that offers several well-documented benefits:

Gut health and live cultures: Many yoghurts contain live bacterial cultures, such as Lactobacillus and Bifidobacterium strains. Check the label for 'live cultures' or 'live and active cultures', as not all yoghurts contain them. It is important to note that any health benefits from live cultures are strain-specific and dose-dependent; they are not universal across all yoghurt products. Regulatory bodies including the European Food Safety Authority (EFSA) apply strict standards to permitted health claims for probiotics.^[13] Some early human research suggests intermittent fasting may influence gut microbiota diversity, but this evidence remains limited and mixed; consuming live-culture yoghurt during the eating window may be a complementary dietary choice, though this should not be overstated.^[10]

Bone health: Yoghurt is a valuable source of calcium and, when fortified, vitamin D and iodine — all important for maintaining bone density and overall health. This is particularly relevant for individuals who may be restricting overall food intake as part of a fasting regimen, as adequate micronutrient intake can sometimes be challenging.

Protein and muscle preservation: One concern with calorie restriction and fasting is the potential loss of lean muscle mass. The high-quality protein found in yoghurt — particularly Greek yoghurt and skyr — provides essential amino acids that support muscle maintenance and repair. This benefit is most meaningful when total protein intake across the eating window is adequate and, ideally, when combined with regular resistance exercise.

Blood glucose regulation: Some evidence suggests that the protein and fat content in plain yoghurt may help moderate post-meal blood glucose rises, which aligns with the insulin-sensitising goals of intermittent fasting. However, individuals with diabetes or pre-diabetes should seek personalised guidance from their GP or diabetes care team before making dietary changes.

Overall, yoghurt represents a well-rounded, evidence-supported food choice within a balanced intermittent fasting plan, provided it is selected carefully with attention to live cultures, sugar content, and micronutrient fortification.

NHS and Dietitian Guidance on Fasting and Dairy Intake

The NHS recommends dairy as part of a balanced diet and acknowledges intermittent fasting as a valid weight management approach; registered dietitians advise yoghurt can be included safely during the eating window, with attention to sugar content and fortification.

The NHS acknowledges intermittent fasting as one of several dietary approaches that some people find helpful for weight management, though it does not endorse a single fasting protocol above others. NHS guidance emphasises that any dietary plan should be nutritionally balanced, sustainable, and appropriate to the individual's health status. The NHS Eatwell Guide recommends dairy or fortified dairy alternatives as part of a healthy diet, highlighting their contribution to calcium, protein, iodine, and vitamin D intake.^[3][4]

NICE guidance relevant to weight management includes CG189 (Obesity: identification, assessment and management), PH53 (Weight management: lifestyle services for overweight or obese adults), and QS111 (Obesity in adults: quality standard).^[7][6] These support personalised dietary approaches delivered within a structured programme. NICE does not currently issue specific guidance on intermittent fasting as a standalone intervention. Registered dietitians in the UK generally advise that dairy foods, including yoghurt, can be incorporated healthily into most eating patterns — including intermittent fasting — provided they are consumed during the eating window and chosen with attention to sugar content and fortification.

From a safety perspective, certain groups should exercise caution with intermittent fasting and seek professional advice before starting:

• People with type 1 or type 2 diabetes: Those taking insulin or sulfonylureas are at particular risk of hypoglycaemia when fasting and should consult their diabetes care team before making any changes.^[11][12] People with type 2 diabetes managed by diet alone or other medications should still seek advice from their care team. Diabetes UK provides patient-facing guidance on fasting and medication safety.

• Pregnant or breastfeeding women

• Those with a history of eating disorders

• Children and adolescents

• Individuals on medications that require food intake at specific times

If you experience severe or persistent dizziness, fatigue, difficulty concentrating, faintness, or any symptoms of hypoglycaemia whilst fasting, stop fasting and seek medical advice promptly. You should contact your GP if symptoms are severe, recurrent, or affecting your safety. A registered dietitian can provide tailored advice on how to structure your eating window — including the role of foods like yoghurt — to meet your nutritional needs safely and effectively. The BDA Food Fact Sheet on intermittent fasting is a useful UK patient-facing resource.

Frequently Asked Questions