Uk food labels

I know of quite a few ready-made products where the weight is completely off. Thus there's quite a lot more in the package than stated on the packaging. As such, the calorie count is higher.

UK labels are governed by the EU food information to consumers regs, which sets out the coversion factors for the calorie calculations (e.g. fat = 9 calories/gram etc.). Article 31 explains the accepted approach, so it can factor in preparation such as cooking if instructions are given. I don't think there are tolerances as such, but this is what's required:

4. The declared values shall, according to the individual case, be average values based on:

(a) the manufacturer’s analysis of the food;

(b) a calculation from the known or actual average values of the ingredients used; or

(c) a calculation from generally established and accepted data.

https://www.dairyscience.info/index.php/packaging/119-labelling-determination-of-the-energy-content-of-food.html

Quote:

The energy information on labels is determined by analysing the chemical composition of a food, the concentrations of protein, fat, carbohydrate for example and adding the energy value of the components to give a total value. Note that methods for determining carbohydrates, including fibre, in food are still the subject of discussion and methods are subject to on-going modification. For more information please see the IFST and Food Standards websites and the report Food energy - methods of analysis and conversion factors that can be downloaded from the FAO website

Where can food manufacturers and others obtain the nutrient composition of foods? Extensive nutritional data for most foods can be obtained from several well characterised and authenticated sources. One that is particularly easy to access is the United States Department of Agriculture's 'National Nutrient Database for Standard Reference . The standard UK reference work is McCance and Widdowson's 'The Composition of Foods'. This reference was updated in 2002 and is now in its sixth edition.

Link: https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid

The human body is not as efficient as a bomb calorimeter in converting food nutrients to energy and this is allowed for in calculating nutrient density. So-called coefficients of digestibility have been determined by several groups and there is general acceptance that humans can utilise the energy in some 97% of carbohydrates, 95% of fats, and 92% of proteins in foods. In general these coefficients are used to adjust the data from bomb calorimetery to obtain more meaningful values for use with people. These coefficients are referred to as Atwater general factors and while they still have utility consideration is being given to their replacement

The calorie counts on labels are basically accurate per 100 grams of food.

However, the weight of the food in the packet doesn't always weigh the same as the weight stated on the packet.

Very advisable to weigh things like pasta / lasagne ready-made meals, because the difference in weight can be quite significant.

The UK has regulations on this. The guidance has more of a focus on not letting companies under sell you quantities rather than over selling. However the actual legislation doesn't differentiate (because I am a nerd and actually downloaded the directive).

Have you ever wondered what the "℮" symbol means next to your packaged product weight? Essentially it means that the product is measured in accordance with certain tolerances. This can be anywhere between 9 and 0.75 percent of the nominal quantity (weight or volume). This depends on the actual weight of the product, and what it is. The smaller the quality, they higher the tolerance. Liquid products have higher tolerances.
For most food items you come across, tolerances will be either 1.5% for between 300-500ml or g. Or 7.5ml or g for between 500-1000ml or g.

It doesn't account for individual portions, just the overall package. Also products are not required to have the ℮ symbol but there are EU trade benefit to having it on your products. That's why you won't be seeing it on goods from the fresh counter.

If you're interested in the reading:
https://www.gov.uk/guidance/packaged-goods-weights-and-measures-regulations

So in answer to your question: if it has an ℮, then you can be fairly sure that the product weight is fairly accurate. The only issue is the actual calorie definition (which shouldn't, (but can) have bias) and the defined serving size (which is often BS, because who drinks half a 500ml bottle of drink? )