How Many Calories Are in Oat Milk

Oat milk has quickly become one of the most popular plant-based milk alternatives in the UK. Valued for its creamy texture and naturally sweet taste, it’s commonly used in coffee, cereals, smoothies, and cooking. But like any food or drink, the calorie content of oat milk varies depending on how it’s made and whether it’s sweetened or fortified. So how many calories are in oat milk, and is it a healthy choice?

Calorie Content by Type and Serving

A standard 250ml glass of plain, unsweetened oat milk contains approximately 90 to 120 calories. Brands vary, with some offering lower-calorie options at around 60 to 80 calories per glass, especially in “light” or reduced-fat versions. Sweetened and flavoured varieties—such as chocolate or vanilla oat milk—can increase the calorie count to 140 or more per 250ml serving.

Barista-style oat milks, which are formulated to froth well for coffee, often contain added oils and therefore more calories, typically around 120 to 130 calories per 250ml.

Homemade oat milk made by blending oats and water, then straining the mixture, tends to be slightly lower in calories unless sugar or oil is added.

Nutritional Breakdown of Oat Milk

Per 100ml, unsweetened oat milk contains about 40 to 50 calories, with around 6 to 8 grams of carbohydrates. Most of those carbohydrates come from natural sugars formed during processing, even when no sugar is added. Fat content ranges from 1 to 3 grams, depending on the brand and whether oils are included. Protein content is relatively low, usually around 1 gram per 100ml.

Many commercial oat milks are fortified with calcium, vitamin D, vitamin B12, and sometimes iodine, making them more nutritionally comparable to cow’s milk. Fibre content can vary but is often minimal due to the straining process, which removes most of the oat solids.

Health Benefits of Oat Milk

Oat milk offers a good option for those avoiding dairy due to lactose intolerance, vegan diets, or ethical reasons. It contains no cholesterol or lactose and is typically low in saturated fat. The carbohydrates in oat milk, especially if it retains some of the soluble fibre beta-glucan from oats, can help support heart health by lowering cholesterol.

Fortified oat milk provides a plant-based source of calcium and B12, both of which are important for bone and nerve health, especially in dairy-free diets. It’s also free from nuts and soy, making it suitable for people with multiple food allergies.

Dietary Drawbacks and Considerations

The main drawback of oat milk is its relatively high carbohydrate and sugar content compared to other plant-based alternatives like almond or soy milk. Even unsweetened oat milk contains natural sugars formed during enzymatic processing, which can raise blood sugar levels. Sweetened or flavoured versions can further increase this effect.

Oat milk is also low in protein, offering much less than cow’s milk or soy milk, which makes it less suitable as a protein source unless combined with other foods. While oat milk can fit into a balanced diet, it's important to check the label for added oils, sugars, and sodium, especially in flavoured or barista-style versions.

Glycaemic Index and Blood Sugar Response

Oat milk has a moderate to high glycaemic index, meaning it can raise blood sugar relatively quickly. This is due to its carbohydrate profile and the natural sugars that develop during processing. For people with diabetes or insulin resistance, unsweetened oat milk is a better choice than flavoured versions, and it should ideally be consumed with a meal containing fibre, fat, or protein to reduce its glycaemic impact.

How Oat Milk Is Made

Oat milk is produced by soaking oats in water, blending the mixture, and then straining out the solids. The remaining liquid is often heated and enzymes are added to break down starches into simpler sugars, giving oat milk its naturally sweet taste. Some brands then fortify the milk with vitamins and minerals, add oil for creaminess, or blend in flavourings for variety.

Homemade oat milk is made using a similar process but without the use of enzymes, resulting in a less sweet and slightly lower-calorie drink, unless sweeteners are added during preparation.

Healthier Alternatives and Comparisons

If you're seeking a lower-calorie milk alternative, unsweetened almond milk usually contains around 30 to 40 calories per 250ml. Soy milk, while slightly higher in calories than almond milk, offers more protein and a similar calorie count to plain oat milk. Coconut milk, while low in carbohydrates, can be high in saturated fat depending on the preparation.

For those who enjoy oat milk but want to reduce their intake of sugar or fat, choosing unsweetened and non-barista options is the best way to keep calories down while still enjoying the taste and texture.

Summary

Oat milk contains between 90 and 130 calories per 250ml depending on whether it’s sweetened, flavoured, or barista-style. It is naturally higher in carbohydrates than other plant milks and has a moderate glycaemic impact, but it is free from dairy, cholesterol, and common allergens. Fortified oat milk can be a nutritious part of a balanced diet, especially for those avoiding animal products, but choosing unsweetened versions is key to keeping sugar and calorie intake under control.