The FastDay Forum

Hello - New to this subject although I did see the BBC program last year and thought it made a lot of sense.

I've been wondering about the accuracy of the nutrition information given on food labels.

Specifically I have a ready meal with a stated calorific value of 445 Kcal. How many calories are there? 445.000 seems improbable. Somewhere between 400 and 600 seems more probable. What tolerances are the supermarkets allowed?

Generally I wouldn't care but on a fast day this becomes increasingly important.

Do the supermarkets actually put their foods through a calorimeter or do they just try to make a sensible guess?

Many thanks

[carorees]

I asked OH who used to do this kind of analysis back in the 80s. He said he thought it was a reasonable guide but not totally accurate.

"For example, for a product that declares 25% fat, the Danish tolerance will be ±15% and the UK ±20%. " - so 25% = 20-30%. Calories are nutrients multiplied by factors, so the same accuracy perhaps ? Calories are not determined by testing.

http://ec.europa.eu/food/food/labelling ... issues.pdf

[carorees]

OH says yes they multiply the fat etc content by a factor to get the calories, e.g. fast grams x 9.

I've not seen horse on any of em either ...just sayin

There were a few stories in newspapers this week on this topic. Some nutritionists pointed out the current system they use to calculate the calorie content doesn't account for calories in fibre and isn't accurate for protein, so it can lead to under and over estimations by up to 25%.

If you're interested the UK uses the Atwater system: calculate the calorie values of individual foods by applying calorie conversion factors to each gram of protein, fat and carbohydrate. So it would be four calories for every gram of protein and nine calories for every gram of fat.

From a biomedical perspective a rough guideline is the best they can ever offer because everyone is different so they will extract more or less energy from the same food depending on a tonne of stuff like genetics and gut flora (the good bacteria in the gut).

There is no evidence for reducing calorie intake by exactly 75% on fast days, so if you're losing weight at a healthy rate you're probably doing it right

Thank you for that.

I'm not relying on the information for dieting purposes or at least not at the level of whether the calorie retriction on diet days is 75% or 74.9% or 75.1%.

Its just useful to know that something that claims 400 cals is probably somewhere between 300 and 500 rather than between 380 and 420.