In this brief article we will answer the question, “does milk break a fast?” and will also highlight the factors which determine whether milk will break a fast.
Does Milk Break A Fast?
The short answer is yes, consuming milk will break a fast. Even one-fourth a cup of milk is sufficient to break a fast.
This is because dairy products contain natural sugars, calories, and carbohydrates. A single cup of milk has 12 grams of carbohydrates which are enough to initiate the release of insulin within the body and break a fast. Milk also has proteins of high digestibility and bioavailability, vitamins and minerals and is 87 % water, which will favor body hydration (1).
What Factors Determine Whether Milk Breaks Fast?
Now that we’ve gotten the short answer, here’s the detailed version: two main factors determine whether milk will break a fast or not.
Type of Fast
If you’re on a clean fast, then consuming anything besides unsweetened tea/black coffee or water will break the fast. A clean fast is ideal for boosting gut cleaning processes and removing dead cells from the body. However, inconsistent findings have been reported to this diet, based on water only, for glucose metabolism, insulin sensitivity, and hypothalamic control of appetite and can lead to adverse effects such as vomiting, nausea, and exacerbation of previous malnutrition (2).
If you’re practicing something known as fasting-mimicking, anything that spikes your insulin level will break your fast, and again, milk qualifies. The goal of fast-mimicking is to keep insulin levels low so that the fat-burning process stays turned on, leading to weight loss. The fasting-mimicking diet, has been recently developed in which a low intake of energy, protein, and sugar is attained to produce metabolic changes similar to fasting while minimizing the harmful effects of a complete lack of food intake. This diet is low in energy, sugars, and proteins, but high in unsaturated fats (2).
Amount of Protein and Carbohydrates in Milk
A single ounce of whole milk contains about 0.9 grams of protein, 0.9 grams of fat, and 1.4 grams of carbohydrates. The latter affects insulin levels the most, while proteins can also initiate the release of insulin but not at the same rate as carbohydrates.
Rule of Thumb: if you’re on the fasting-mimicking regime keep the total quantity of carbohydrates and protein less than one gram. This means that you can safely consume 0.5 grams of carbs and 0.5 grams of protein without breaking your fast. But since a single ounce of milk contains more than one gram of both, it will certainly break the fast.
Does Coffee With Milk break a fast?
Coffee with milk can break a fast depending on the quantity of milk used.
As mentioned in the previous section, a single ounce of milk contains 1.4 grams of carbohydrates and 0.9 grams of fat.
To keep their combined amount less than one gram and to avoid a possible insulin spike, you would need to add as little as 0.75 tablespoons of milk to your coffee. A better option would be adding heavy whipping cream since it is lower in both protein and carbohydrates.
What Happens to Your Body During Fasting?
During fasting, which means refraining from consuming food, your body experiences various metabolic changes. After a certain period, your body eventually enters into a state of ketosis in which fat is burned for energy production since carbohydrates are no longer available. Ketosis is a metabolic state whereby the body generates most of its energy requirements (in the form of adenosine triphosphate) from ketones rather than carbohydrate (in the form of glucose). It can be achieved through prolonged fasting (longer than 72 hours) or following a strict ketogenic diet – a very low-carbohydrate, moderate-protein, high-fat diet – for several days to weeks. Skeletal muscles and the brain can use ketones for energy production under aerobic conditions (3).
Fasting also results in a fall in insulin levels and boosts autophagy, a process by which the body gets rid of damaged, harmful, or unneeded cells.
Evidence also suggests that intermittent fasting can cause significant weight loss, lower blood sugar, improve heart health, reduce inflammation, and decrease the chances of developing chronic diseases. Intermittent fasting is an approach that not only restricts calories but also promotes maintenance and recovery. Studies have shown that intermittent fasting resulted in some degree of weight loss, ranging from 2.5 to 9.9%, and fat mass loss, but it can also lead to adverse effects. In addition, a fasting-mimicking diet is effective at reducing insulin resistance and regulating appetite-regulating hormones as well as preserving muscle mass (2).
Most fasting patterns involve 12 to 16 hours of continuous fasting each day, while some involve fasting for 24 or 48 hours once or twice a week.
What Can You Eat While Fasting?
Here are certain foods and beverages you can eat during fasting (4).
- Plain or carbonated water contains zero calories and will help you stay hydrated during a fast.
- Tea and coffee should ideally be taken without sugar, cream, or milk. However, certain people find that a small amount of fat or milk can suppress their hunger.
- Drinking one to two teaspoons (5 to 10 ml) of diluted apple cider vinegar mixed with water can help you stay hydrated and suppress cravings.
- Even though healthy fats such as MCT oil, coconut oil, ghee, or butter break a fast, they don’t break ketosis.
- Bone broth is rich in nutrients and will technically break your fast, but it will help recover lost electrolytes if you were consuming only water during the fast. However, limited amounts of this high-fat, low-carb, and moderate-protein broth will not interfere with ketosis.
In this brief article we answered the question, “does milk break a fast?” and also highlighted the factors which determine whether milk will break a fast.
If you have any more questions or comments please let us know.
- Pereira, Paula C. Milk nutritional composition and its role in human health. Nutrition, 2014, 30, 619-627.
- Sadeghian, M., Hosseini, S.A., Zare Javid, A. et al. Effect of Fasting-Mimicking Diet or Continuous Energy Restriction on Weight Loss, Body Composition, and Appetite-Regulating Hormones Among Metabolically Healthy Women with Obesity: a Randomized Controlled, Parallel Trial. Obes Surg, 2021, 31, 2030–2039
- Scott, Jonathan M., and Patricia A. Deuster. Ketones and Human Performance. J. special oper med, 2017, 17,112-116.
- Panoff, L. What breaks fast? Food, drinks and supplements. 2019. Healthline nutrition.
- Gibson, S. A., and P. Gunn. What’s for breakfast? Nutritional implications of breakfast habits: insights from the NDNS dietary records. Nutr Bull, 2011, 36, 78-86.