High-Calorie Overnight Oats for Weight Gain (600+ Cals)

A jar of high calorie overnight oats for weight gain has 600 to 900 calories, against about 200 for a light jar made with skimmed milk. The difference is what you soak the oats in and stir through: whole milk, full-fat yoghurt, nut butter and seeds. The weight gain jar below is about 790 calories and 28g of protein.

Written by James Frost, founder of Flaming Phoenix. Updated October 2026.

Calories are worked out from McCance and Widdowson's CoFID 2021 food tables for the gram weights given, except chia seeds, which CoFID does not list; those come from the Linwoods chia label (482 calories per 100g). Everything is rounded to the nearest 10. I started Flaming Phoenix in 2024 after about 150 conversations with endurance athletes, expedition people and people who struggle to eat enough. This page sits alongside my wider how to gain weight guide; if you would rather have something crunchy, see high-calorie granola, and for a hot bowl, high calorie porridge.

Are overnight oats good for weight gain?

Yes, when they are built for it: overnight oats made with whole milk, full-fat yoghurt and nut butter give 600 to 900 calories in a jar that is ready before you are awake.

The NHS suggests adding around 300 to 500 calories a day to gain weight gradually. Swapping a light jar (40g of oats soaked in 150ml of skimmed milk, about 200 calories) for the 790-calorie jar below adds about 590, which covers the whole of that increase from one change.

They are also easier to keep up than most weight gain breakfasts. The work takes three minutes the evening before and none in the morning, which removes a common reason people skip breakfast calories. Oats that have soaked overnight are soft and cold and need little chewing, which puts them among the more useful soft high-calorie foods when you are not hungry. And the base takes almost any add-in without changing the method.

The add-ins decide whether a jar is high or low calorie. 60g of oats in 200ml of whole milk is about 350 calories. The same oats with yoghurt, peanut butter, chia, honey and a banana come to about 790.

How to prepare overnight oats for weight gain

To prepare overnight oats for weight gain, stir rolled oats into whole milk and full-fat yoghurt with nut butter and chia seeds, seal the jar and leave it in the fridge for at least five hours. Step by step:

1. Put 60g of rolled oats in a jar or tub with a lid.
2. Add 200ml of whole milk and 100g of full-fat Greek-style yoghurt and stir well, so no dry oats are left at the bottom.
3. Stir in 20g of peanut butter (a heaped tablespoon), 15g of chia seeds and 10g of honey, plus cinnamon or vanilla if you like.
4. Seal and refrigerate for at least five hours, ideally overnight. The oats and chia soak up the liquid and thicken.
5. In the morning, slice a banana on top. Eat it cold, or warm it in the microwave if you prefer.

The working for one jar, about 790 calories and 28g of protein:

• Rolled oats, 60g: 230 calories and 6.5g of protein.
• Whole milk, 200ml: 125 calories and 7g of protein.
• Full-fat Greek-style yoghurt, 100g: 135 calories and 6g of protein.
• Peanut butter, 20g: 120 calories and 5g of protein.
• Chia seeds, 15g: 70 calories and 3g of protein.
• Honey, 10g: 30 calories.
• Banana, 100g peeled: 80 calories and 1g of protein.

If you make two or three jars at once, keep them in the fridge and go by the use-by dates on the milk and yoghurt.

High calorie overnight oats recipes from 500 to 1,000 calories

The same method works at any size. Four variations on the jar above:

Small jar, about 490 calories. 40g of oats, 150ml of whole milk, 50g of Greek-style yoghurt, 15g of peanut butter, 10g of chia and half a banana. For mornings when a full jar is too much.

Higher protein jar, about 860 calories and 35g of protein. The standard jar with 20g of skimmed milk powder whisked into the milk first. That adds 7g of protein without making the jar any bigger, and no protein powder is needed.

1,000 calorie jar. 80g of oats, 250ml of whole milk, 100g of Greek-style yoghurt, 30g of peanut butter, 15g of chia, a banana and 25g of raisins. About 1,000 calories and 35g of protein in roughly 600g of food, so use a big jar.

Vegan jar, about 760 calories. 60g of oats soaked in 200ml of sweetened soya drink and 100ml of tinned coconut milk (the tin, not the carton drink), with 20g of peanut butter, 15g of chia and a banana. About 23g of protein.

What can I mix with oats to gain weight?

Mix the oats with whole milk or full-fat yoghurt first, then add one fat and one sweet thing: nut butter, seeds or tinned coconut milk, and banana, dried fruit or honey. Per typical portion:

• Tinned coconut milk, 100ml: about 170 calories, swapped for some of the milk.
• Walnuts, 20g chopped: about 140 calories; add them in the morning so they stay crunchy.
• Full-fat Greek-style yoghurt, 100g: about 135 calories and 6g of protein.
• Peanut butter, 20g: about 120 calories and 5g of protein.
• Pumpkin seeds, 15g: about 85 calories and 4g of protein.
• Banana, 100g peeled: about 80 calories.
• Plain chocolate, 15g grated: about 75 calories.
• Raisins or chopped dates, 30g: about 70 to 75 calories.
• Chia seeds, 15g: about 70 calories and 3g of protein, and they thicken the jar as they soak.
• Skimmed milk powder, 20g: about 70 calories and 7g of protein.

Chia and milk powder both take up liquid, so add a splash more milk if the jar sets too thick. The same idea of building calories into the food you already eat runs through my high-calorie breakfast guide, which covers eggs, toast and smoothies too.

Which oats are best for weight gain?

Rolled oats, sold in the UK as porridge oats, are best for overnight oats, and the type of oat makes little difference to the calories: about 375 to 380 per 100g dry.

CoFID gives 381 calories per 100g for porridge oats and Quaker's label 374 for its rolled oats, so a gram of one oat is much like a gram of another. Texture is what changes. Jumbo oats work and stay chewier; steel-cut (pinhead) oats stay hard without cooking; instant oats go soft and pasty overnight. If you need to avoid gluten, choose oats labelled gluten-free.

How to eat overnight oats with a small appetite

Make the jar smaller but richer: the 490-calorie small jar above keeps the peanut butter and chia but uses less oats and milk, so there is less to get through.

Stir the dense extras through rather than piling them on top, so the jar barely grows. If even a spoonful feels like too much, blend the same ingredients with extra milk into a drink, which is often easier to sip than to eat; my homemade weight gainer shakes guide has more. And make tomorrow's jar at the time of day when your appetite is best, so breakfast is already waiting.

If you are losing weight without trying, or your appetite has dropped suddenly, it is worth speaking to your GP.

What if you forgot to make overnight oats?

Have something dense that needs no preparation: a 150g pot of full-fat Greek-style yoghurt with a 30g handful of mixed nuts is about 370 calories, and a bagel with peanut butter and banana about 500.

Our weight gain bars are another option for those mornings. Phoenix Bars have up to 557 calories in only 120g, with up to 19g of protein, and can be eaten as they are or stirred into water or milk as a quick high-calorie porridge. They are vegan and gluten-free, so they suit the same diets as the vegan jar above.

Frequently asked questions

Are overnight oats high in calories? Not by default. 40g of oats soaked in 150ml of skimmed milk is about 200 calories, half the 400 that Public Health England uses as its breakfast guide. They become high in calories when a recipe stacks whole milk, yoghurt, nut butter, seeds and honey into one jar, which is why some versions reach 800 or more.

How many calories should high-calorie overnight oats have? It depends on your overall intake, but a genuinely high-calorie jar built for weight gain typically lands between 600 and 900 calories. The recipe above is about 790 and goes past 1,000 with more oats, peanut butter and raisins. 600 is half as much again as the 400 calorie breakfast guide, so it is a lot for most people and normal for someone gaining weight.

Do overnight oats make you gain weight? Only if they take your total for the day above what you use. A light 200-calorie jar will not on its own, while a 790-calorie jar eaten every day on top of your usual food very likely will, which is the aim if you are trying to gain. Weight follows the whole day's calories, not oats in particular.

Are overnight oats or porridge better for gaining weight? Both work; the difference is convenience and texture. Overnight oats are made ahead and eaten cold, which suits busy mornings and a small appetite, while high calorie porridge is warm and made fresh. Either can be made high-calorie with the same add-ins, so the best one is whichever you will actually eat consistently.

Can I make high-calorie overnight oats vegan or gluten-free? Yes. Use a full-fat plant drink or tinned coconut milk and a dairy-free yoghurt for a vegan version, and oats labelled gluten-free for a gluten-free one. Peanut butter, chia and banana keep both versions calorie-dense; the vegan jar above is about 760 calories.

Is it okay to eat overnight oats every day? Yes, for most people. Oats are a wholegrain, and the British Heart Foundation points to 3g of oat beta-glucan a day, within a balanced diet, as an amount shown to lower cholesterol. Rotate the add-ins (nuts one week, dates and pumpkin seeds the next) so the jar stays appealing.

Sources: McCance and Widdowson's Composition of Foods Integrated Dataset (CoFID 2021), GOV.UK; Linwoods Organic Whole Chia Seeds nutrition label, Sainsbury's; Quaker UK, Traditional Rolled Oats; NHS, Healthy ways to gain weight; Public Health England, 400-600-600 guidance, GOV.UK; British Heart Foundation, Porridge: is it a healthy breakfast?.