High calorie bar recipe: 418 kcal bars and a 25g protein bar

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

Homemade high calorie bars are oat bars built on peanut butter, coconut oil, golden syrup and dates, and a good batch gives 400 to 500 calories a bar. My recipe below adds up to 4,175 calories, which is about 418 calories a bar cut into 10, or 522 cut into 8.

I make high calorie bars for a living, and I still think anyone who needs calorie-dense food should know how to make it at home. Below is the recipe with every number shown, a no-bake protein version, ways to push the calories higher, and a straight answer on when buying makes more sense.

High calorie bar recipe: 418 calories a bar (vegan and gluten free)

This makes 10 sturdy bars of about 418 calories, or 8 bigger, more fragile bars of about 522. Calories come from the UK labels listed on Ocado, checked in October 2026. Hands-on time is about 15 minutes, plus 30 minutes in the oven and two hours to cool and chill.

Ingredients:

• 250g porridge oats: 923 kcal (Mornflake, 369 per 100g). Use certified gluten-free oats if the bars need to be gluten free.
• 150g smooth peanut butter: 890 kcal (Pip & Nut, 593 per 100g)
• 120g coconut oil: 1,079 kcal (pure fat at about 9 calories a gram; the Biona label gives 899 per 100)
• 140g golden syrup: 455 kcal (Lyle's, 325 per 100g)
• 60g light brown or light muscovado sugar: 235 kcal (Billington's, 392 per 100g)
• 60g pumpkin seeds: 339 kcal (Mintons Good Food, 565 per 100g)
• 80g chopped dates: 254 kcal (Whitworths, 317 per 100g)
• 1 tsp vanilla extract and half a tsp fine salt: too little to count

The sum: 923 + 890 + 1,079 + 455 + 235 + 339 + 254 = 4,175 calories for the batch. Divided by 10 that is 418 calories a bar; divided by 8 it is 522.

Per bar, cut into 10: 418 calories, 39g carbohydrate, 24g fat and 9g protein. The raw mixture weighs 860g, so each bar starts at about 86g before baking.

Method:

1. Heat the oven to 160C fan (180C, gas 4) and line a 20cm square tin with baking paper, leaving an overhang to lift the slab out.
2. Melt the coconut oil, golden syrup, sugar and salt together in a large pan over a low heat, stirring until the sugar has dissolved.
3. Take the pan off the heat and stir in the peanut butter and vanilla until smooth.
4. Fold in the oats, seeds and dates until every oat is coated. The mixture should look almost too wet; that is what binds it.
5. Tip into the tin and press down very firmly with the back of a spoon or the base of a glass. Of all the steps, firm pressing does the most to make bars hold together.
6. Bake for 25 to 30 minutes until golden at the edges. It will still feel soft; that is correct.
7. Cool completely in the tin, then chill for at least an hour before cutting into 10 bars with a sharp knife.

Storage: 5 to 7 days in an airtight container, a little longer in the fridge, or up to 3 months wrapped individually and frozen.

No-bake option: skip the oven, press the mixture into the tin and chill for 2 hours instead. The bars come out softer, need to live in the fridge, and are best eaten within 4 to 5 days. For a film-inspired twist, my guide to Kalteen bars, the fictional bars from Mean Girls, includes a recipe of its own.

Prefer a classic butter-and-syrup tray bake? My high calorie flapjack recipe comes in at 485 calories a square, and there are separate recipes for vegan flapjacks and gluten free flapjacks.

High calorie protein bar recipe (no-bake, 25g protein)

For a high calorie protein bar, swap the coconut oil and sugar for whey protein and ground almonds and skip the oven: six bars come out at about 466 calories and 25g protein each.

Ingredients (makes 6 thick bars, or 8 smaller ones):

• 150g porridge oats: 554 kcal and 17g protein (Mornflake)
• 150g smooth peanut butter: 890 kcal and 41g protein (Pip & Nut)
• 100g vanilla whey protein powder: 390 kcal and 75g protein (The Organic Protein Co.)
• 100g golden syrup: 325 kcal (Lyle's)
• 60g ground almonds: 367 kcal and 13g protein (Ocado, 612 per 100g)
• 50g dark chocolate chips, melted, for the top: 269 kcal and 3g protein (Dr. Oetker, 537 per 100g)
• 2 to 4 tbsp water, to bring it together

The sum: 554 + 890 + 390 + 325 + 367 + 269 = 2,795 calories, and 17 + 41 + 75 + 13 + 3 = 149g protein (the syrup adds under 1g). Cut into 6, that is 466 calories and 25g protein a bar; cut into 8, it is 349 calories and 19g.

Method:

1. Line a 900g (2lb) loaf tin, about 21 x 11cm, with baking paper.
2. Warm the peanut butter and golden syrup together in a pan over a low heat for a minute or two, just until runny.
3. Mix the oats, protein powder and ground almonds in a bowl, pour in the warm peanut butter mixture and stir.
4. Add water a tablespoon at a time until a handful holds together when squeezed. Protein powders soak up different amounts, so go slowly.
5. Press very firmly into the tin, spread the melted chocolate over the top and chill for at least 2 hours.
6. Lift out and cut into 6 thick bars.

Storage: in an airtight box in the fridge for up to 5 days, or wrapped and frozen for up to 3 months.

Whey is not vegan. For a vegan bar, use a pea or soy protein powder and recount from its label, because calories and protein vary a lot between powders. For gluten free, use certified gluten-free oats and check the protein powder label as well.

Why is it so hard to make a bar over 450 calories at home?

It is hard because a bar big enough to reach 500 calories tends to break, not because home ingredients lack calories.

Per gram, the raw mixture above is already very dense: 4,175 calories in 860g is about 4.85 calories per gram, more than a Blackfriars Original Flapjack (443 calories per 100g). To match the 557 calories of my Cherry Bakewell bar from this mix you would need a 115g piece (557 divided by 4.85), and the bigger an oat bar gets, the more easily it snaps.

Fat is the second limit. The NHS notes that a gram of fat provides 9 calories against 4 for carbohydrate and protein, so the obvious route to a denser bar is more fat. But fat does not bind. Push past a certain ratio and the mixture stops being a bar and turns into greasy rubble; golden syrup and hard pressing are what hold it together.

The third limit is taste. One homemade bar is lovely. The fourth on a long day, or the tenth across a hard week, is a different experience, because the syrup that binds the bar also makes it very sweet. If you will eat several a day, vary the flavour (cinnamon, cocoa, ground ginger) or alternate the bars with savoury food.

How do you make homemade bars even higher in calories?

Add fat in forms that do not wreck the structure. Each change below is for one batch of the main recipe, using the same labels:

• Stir in 40g chopped mixed nuts: +264 calories (Whitworths, 661 per 100g).
• Increase the peanut butter from 150g to 180g: +178 calories.
• Brush the pressed mixture with 1 tablespoon (15g) of melted coconut oil before baking: +135 calories.
• Swap 30g of the oats for 30g ground almonds: +73 calories (612 minus 369, times 0.3).

Do all four and the batch rises from 4,175 to 4,825 calories (264 + 178 + 135 + 73 = 650 extra), or 483 a bar cut into 10. What I would avoid: more loose oil in the pan (greasy bars), chocolate chunks stirred through a warm mixture (they melt and thin the binding), and fresh fruit (the moisture shortens shelf life). If drinks suit you better than bars, homemade weight gainer shakes add several hundred calories with no binding problem at all.

Should you make or buy high calorie bars?

Make them if you will eat them at home within a week; buy them if they need to travel, keep for months or appear without any effort.

At Ocado prices in October 2026 the main batch costs about £5.16: oats 47p, peanut butter £1.13 (at its full £7.50 a kilo), coconut oil £1.28, golden syrup 57p, sugar 27p, pumpkin seeds 77p and dates 67p. That is about 52p a bar, or roughly 12p per 100 calories. Certified gluten-free oats cost more (Primrose's Kitchen is £10.75 a kilo), which adds about £2.22 a batch and takes each bar to about 74p.

A homemade bar keeps for about a week; Phoenix Bars, with up to 557 calories in only 120g, keep for up to two years. Homemade bars vary from batch to batch and crumble if you cut them big; ours are soft and made to the same recipe every time. Customers have taken them to some unforgiving places. Shaun Weston, on a South Pole expedition, found them "Easy to eat, even at -45c", and Adam Eustace, bikepacking across Vancouver Island, said they "Didn't break up in my bag". That matters for a race plan or lightweight backpacking food.

My steer: if you enjoy baking and will eat them within the week, make them. If you need calories that travel, keep, or simply appear on the days when effort is the whole problem, buy. The best energy bars for weight gain and the highest calorie bars in the UK compare the bought options.

Using homemade bars for weight gain or a small appetite

If you are building weight gradually, the NHS suggests adults could try adding around 300 to 500 extra calories a day, and one 418-calorie bar alongside normal meals covers most of that in a few unhurried bites. Its guide to healthy ways to gain weight is a sensible starting framework, and it also advises speaking to a GP if you have lost weight without trying.

On days when appetite is low, small and gentle beats big and ambitious. Cut a bar into six chunks and have one with a cup of tea through the day, or crumble half a bar into warm milk so it softens into something closer to high calorie porridge, which can be easier than chewing when eating feels like work. There are more low-effort ideas in my guides to what to eat when your appetite is low and easy ways to eat more calories, and the principle behind all of it is choosing calorie-dense foods that hold more calories in each bite.

Homemade high calorie bar FAQs

Why do my homemade bars fall apart?
Almost always one of three things: the mixture was not pressed firmly enough into the tin, the bars were cut while warm, or the fat-to-syrup ratio drifted too far towards fat. Press hard, cool completely, chill before cutting, and keep the syrup in, because it is the binder.

How long do homemade high calorie bars last?
About 5 to 7 days in an airtight container at room temperature, slightly longer in the fridge, and up to 3 months frozen if wrapped individually. Home bars have no preservative system, which is one of the biggest practical differences from shop-bought bars with dated shelf lives of months or years.

How many calories should a high calorie bar have?
There is no official definition. I would call anything over 300 calories high calorie, and 400 to 500 is very good for homemade. For scale, a Blackfriars Original Flapjack has 443 calories per 100g, and the highest-calorie bars you can buy in the UK reach the mid-500s per bar.

Can I make these bars gluten free and vegan?
Yes, the main recipe already is, provided you buy certified gluten-free oats, since standard oats are often cross-contaminated. If you are building a wider plan around those needs, my guide to high calorie gluten free foods covers the options beyond bars, and my comparison of the best vegan energy bars lines up ready-made ones.

Can you make a high calorie bar without protein powder?
Yes. The main recipe uses no powder at all and still gives 9g protein a bar, from the oats, peanut butter and pumpkin seeds. Protein powder only matters if you want 20g or more in a single bar, which is what the no-bake version above is for.

What are the best snacks to eat alongside these bars?
Variety protects you from palate fatigue, so rotate bars with other calorie-dense options like nuts, nut butter on toast, full-fat yoghurt and dried fruit. My full list of high calorie snacks ranks the easiest ones.

Sources: NHS, Fat: the facts; NHS, Healthy ways to gain weight; ingredient labels and prices on Ocado, October 2026: Mornflake oats, Pip & Nut peanut butter, Biona coconut oil, Lyle's golden syrup, Billington's sugar, Mintons pumpkin seeds, Whitworths dates, The Organic Protein Co. whey, Ocado ground almonds, Dr. Oetker chocolate chips, Whitworths mixed nuts, Primrose's Kitchen gluten free oats; Blackfriars Bakery, Original Flapjack.