Doubly Labelled Water (DLW) is said to be the "gold standard" of energy measurements but in the world of nutritional research that probably means it's just the least worst option. Most of the materials I've read propose it as a good measure of energy expenditure and it is then combined with body weight and composition changes to determine what the energy intake "must have been" using the calorie hypothesis.
DLW is in the news today as the UK Government's "Nudge Unit" - now operating independently as Behavioural Insights - has been looking at alleged under-reporting of calorie intake in official statistics.
One aspect of accuracy is how repeatable a measure is - if you take the same person and repeat a DLW test in the same circumstances do you get the same answer ? This has been done :-
Monday, 8 August 2016
Sunday, 7 August 2016
UK retailer Marks & Spencer has filed a claim with the European regulator EFSA for their "Balanced for You" range of ready meals with a limited ratio of carbohydrate to protein.