For a shorter 5 km run, you do not automatically need a biscuit: University College London Hospitals NHS Foundation Trust says snacks for shorter activities may only be needed to prevent or treat low blood glucose. If you want a digestive while cutting back on sugar, compare the sugars and total carbohydrate in the portion you would eat. McVitie’s The Light One lists 1.3 g sugars per biscuit, while Siro’s sugar-free digestive still lists 9.5 g carbohydrate per 13 g portion and carries a warning about excessive consumption.
You are deciding whether to eat around a 5 km run, rather than treating a biscuit as a required part of every run. University College London Hospitals NHS Foundation Trust notes that snacks for shorter activities may only be needed to prevent or treat low blood glucose.
You want to keep eating digestives while comparing the sugars, total carbohydrate and portion size shown on different packs.
You need to distinguish an everyday lower-sugar biscuit from your planned approach to exercise-related low blood glucose. Cambridge University Hospitals NHS Foundation Trust advises people taking glucose-lowering medicines such as insulin or sulphonylureas to be aware of how exercise affects their blood glucose.
Decide whether you want a snack at all, then compare the portion you would eat with the per-100 g declaration.
| Priority | What to check | Your needs |
|---|---|---|
| Snack timing | Consider the run’s duration and when you last ate. University College London Hospitals NHS Foundation Trust says shorter activities may only call for a snack to prevent or treat low blood glucose. | I do not want to eat an extra biscuit simply because I have a short run planned. If I manage low blood glucose, I follow my individual exercise plan rather than treating a reduced-sugar digestive as fast-acting treatment. |
| Sugars and portions | Read sugars per biscuit and per 100 g, alongside total carbohydrate. Tesco’s listings give 1.3 g sugars and 9.2 g carbohydrate per McVitie’s The Light One biscuit, versus 2.0 g sugars and 9.0 g carbohydrate per 14 g Tesco standard digestive. | I want less sugar in the biscuit I actually eat, without assuming a reduced-sugar claim describes its total carbohydrate or the size of my portion. |
| Sweeteners | Check ingredients as well as sugars and carbohydrate. Sainsbury’s lists less than 0.1 g sugars and 9.5 g carbohydrate per 13 g Siro portion; its listing warns that excessive consumption may have laxative effects. | Before a run, I would rather know whether a sugar-free biscuit contains a sweetener I am unfamiliar with than choose by the sugar figure alone. |
| Ingredients | Read the current pack’s ingredient and allergen declaration, particularly if an allergy or intolerance applies. Check the portion information again if the recipe or pack changes. | I need to know what is in the particular biscuits I buy, not assume that changing the sugar claim changes their allergens. |
McVitie’s The Light One lists 8.9 g sugars per 100 g. The NHS food-label guide defines low total sugars as 5 g or less per 100 g; the manufacturer’s 30%-less-sugar statement compares it with an average digestive.
Read the per-100 g figure and your likely portion separately. Do not treat the comparison as a claim about calories or running performance.
Sainsbury’s listing for Siro digestives shows carbohydrate despite the sugar-free label, and warns of laxative effects with excessive consumption.
Check the sweeteners and portion information before making an unfamiliar biscuit a pre-run snack.
A per-biscuit figure describes that biscuit’s serving size as well as its recipe. The Tesco and Sainsbury’s standard digestives checked have different portions.
Use per-100 g figures to compare recipes, then per-biscuit figures to assess how much you plan to eat.
The Light One is the reduced-sugar digestive in this comparison. Its 30%-less-sugar wording is a manufacturer comparison with an average digestive, not a claim about running performance.
Tesco’s standard own-label digestive provides a portion comparison, rather than a reduced-sugar alternative.
Sainsbury’s standard own-label digestive is another portion reference. The Siro sugar-free biscuit listed by the retailer is a separate brand.
Its UK-listed digestive offers a per-100 g reference, rather than a stated reduced-sugar option.
Its sugar-free digestive is an alternative for comparing labelled sugars with total carbohydrate.
This sugar-free-labelled digestive is an option if you want to compare sugars and carbohydrate before choosing a biscuit around a 5 km run.
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A 400 g pack of digestives labelled sugar-free. If you are considering them before a run, check the current pack for carbohydrate per portion, sweeteners and allergens rather than relying on the sugar-free wording alone.
No. Sainsbury’s lists 9.5 g carbohydrate per 13 g portion of Siro sugar-free digestives, despite listing less than 0.1 g sugars. Check both figures for the particular biscuit you choose.
Do not assume it is suitable fast-acting treatment. University College London Hospitals NHS Foundation Trust distinguishes snacks for shorter activities from managing hypoglycaemia; follow your individual diabetes plan for exercise-related low blood glucose.