Long-run fuel testers
If you are rehearsing what and when to eat, a labelled portion lets you count its carbohydrate. London Marathon Events recommends using long runs to find out which carbohydrates agree with you.
Who might use each format?
One-portion carriers
If carrying a defined portion matters, distinguish the individually wrapped bar from a pack of three or four separate cakes. Their labelled carbohydrate amounts differ.
Allergen-conscious shoppers
Check the current pack’s ingredients and precautionary information for the exact product you intend to eat. Recipes and allergen statements differ across the Jaffa Cakes listed by retailers.
What should you check before choosing?
Start with the portion you would carry and eat, then check its label and try that arrangement during training.
| Priority | What to check | Your needs |
|---|---|---|
| Carbohydrate per portion | Check whether the figure is per bar, cake or pack. Tesco lists 15.5 g carbohydrate per McVitie’s bar, 22.8 g per three-cake serving and 30.3 g per four-cake pack. | I want to count the portion I will actually eat, rather than mistake its sugars or calories for total carbohydrate. |
| Carrying format | Check for an individual wrapper or a defined group of cakes. A bar is one piece; the other listed McVitie’s portions contain three or four cakes. | A ready-packed single piece may suit my carrying plan, or I may prefer to eat a small pack of original cakes. |
| Training trial | Try the exact product, portion and timing on a long run. London Marathon Events advises using training to find which carbohydrates agree with you; a product label cannot predict that. | I need to find out how this food fits alongside what I drink and eat during my runs. |
| Ingredients | Read the current pack’s ingredients and allergen information. Do not transfer details from another recipe or a similarly named listing. | If an ingredient matters to me, I need information for the particular pack I am buying. |
What mistakes should you avoid?
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Treating a bar and a pack of cakes as the same portion
Tesco lists 15.5 g carbohydrate per McVitie’s bar, compared with 22.8 g per three-cake serving and 30.3 g per four-cake pack.
Compare the carbohydrate in the portion you intend to carry and eat, then trial that portion during training.
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Relying on an online ingredient list for an allergy decision
Retailer listings show different recipes and allergen information across Jaffa Cake products, and Waitrose notes that recipes can change.
Read the ingredients and precautionary statements on the current physical pack before eating.
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Copying nutrition figures between similarly named snack packs
Tesco’s McVitie’s six-by-three listing gives 69.6 g carbohydrate per 100 g, while the checked Joybuy listing gives 67.1 g per 100 g. Their figures should not be treated as interchangeable.
Use the label on the exact pack you buy when working out its portion.
Which brand ranges are relevant?
McVitie’s
The checked UK listings include an individually wrapped Jaffa Cake bar and original cakes in three- and four-cake portions.
- Tesco lists 15.5 g carbohydrate per bar, 22.8 g per three-cake serving and 30.3 g per four-cake pack.
- Those label figures do not establish how a portion will suit an individual run.
Tesco
Its checked own-label Orange Jaffa Cake Spongy & Fruity twin pack is a box-based alternative to a single bar.
- Tesco lists 9.3 g available carbohydrate per cake for this product.
- The listing says to keep the opened product airtight and consume it within two days.
Sainsbury’s
Its checked 24-cake own-label product offers loose cakes rather than a single bar.
- Sainsbury’s lists 8.2 g carbohydrate per cake for this product.
- Use that product’s serving figure rather than a McVitie’s portion figure.
M&S
Its checked dark-chocolate orange Jaffa Cakes are another loose-cake format.
- Ocado lists 7.6 g carbohydrate per 11.4 g cake.
- Ocado’s listing includes milk and warns that the product is not suitable for people with nut or peanut allergies; check the current pack.
Waitrose
Its checked Mini Jaffa Cakes can be measured into a serving rather than bought as one defined bar.
- Waitrose lists 15.6 g carbohydrate per 25 g serving, not per cake.
- Waitrose advises checking the pack label because recipes may change.
Joybuy Jaffa Cake options
These options cover a three-cake snack-pack format and a larger box from which you can make your own portions. Neither is the individually wrapped single bar discussed above.
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McVitie’s The Original Jaffa Cakes Snack Pack 6 x 3pk 198g
Consider the three-cake pack format if you want a defined portion to trial on a training run, rather than one solid bar. Check the carbohydrate figure on the pack you receive: the checked Joybuy and Tesco listings for nominally similar six-by-three products give different nutrition figures.
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McVitie’s 80 Jaffa Cakes 1.07kg
This 80-cake box suits making your own portions for training trials. You would need to portion and carry the cakes yourself; check the pack’s per-cake information before calculating what you plan to eat.
Frequently asked questions
Should I compare calories or carbohydrate for the portion?
Use the label’s total carbohydrate figure to compare the portions you intend to eat; calories and “of which sugars” describe different measures. Tesco lists 15.5 g carbohydrate and 11.6 g sugars per checked McVitie’s bar.
Should I try a Jaffa Cake bar for the first time on marathon day?
Try it during training instead. London Marathon Events advises using long runs to test when and how much you eat and which carbohydrates agree with you; that guidance does not establish that a particular bar will suit you.
Can a Jaffa Cake bar replace a fuelling and hydration plan?
No: its label describes one food portion, not everything you will eat and drink on a run. London Marathon Events advises testing both fuelling and hydration arrangements during long training runs.
How should I check allergens in a wrapped snack?
Read the ingredients and allergen information on the current pack of the exact product. UK government food-labelling guidance requires prepacked food to carry an ingredients list including allergens, while the checked Jaffa Cake listings show recipe-specific differences.
Are supermarket Jaffa Cakes the same portion size as McVitie’s?
Do not assume their per-cake figures match. The checked retailer listings give 9.3 g available carbohydrate per Tesco own-label cake, 8.2 g carbohydrate per Sainsbury’s cake and 7.6 g per M&S cake; check each pack’s serving definition before planning a portion.