ISSN 0254-4725
                                                                                                                                                                                  7
                                                                                                                                                                                  7          Food energy – methods                                                                       FAO
                                                                                                                                                                                                                                                                                 FOOD AND
                                                                                                                                                                                                                                                                                 NUTRITION
                                                                                                                                                                                             of analysis and                                                                          PAPER
                                                                                                                                                                                             conversion factors                                                                        77
                                                                                                                                                                                  F
                                                                                        Assessing human energy and nutrient requirements has been a                               o
                                                                                                                                                                                  o
                                                                                       longstanding activity of FAO’s Food and Nutrition Division and is                          d
                                                                                                                                                                                   
                                                                                                                                                                                  e
                                                                                       considered an ongoing activity requiring continual review. Energy                          n
                                                                                                                                                                                  e
                                                                                                                                                                                  r
                                                                                   requirements need to be linked to the energy availability from foods, and                      g
                                                                                                                                                                                  y
                                                                                                                                                                                   
                                                                                   this depends on knowing the amounts of energy-providing components in                          –
                                                                                                                                                                                   
                                                                                      foods and expressing the energy values clearly and unambiguously.                           m
                                                                                                                                                                                  e
                                                                                                                                                                                  t
                                                                                      Because there are various methods of analysis of the macronutrient                          h
                                                                                                                                                                                  o
                                                                                        content in foods and numerous ways of expressing the energy                               d
                                                                                                                                                                                  s
                                                                                                                                                                                   
                                                                                      values of foods there is a need to standardize and harmonize energy                         o
                                                                                                                                                                                  f
                                                                                                                                                                                   
                                                                                                               conversion values.                                                 a         Ingested energy (IE) = gross energy (GE)
                                                                                                                                                                                  n
                                                                                      The Technical Workshop on Food Energy – Methods of Analysis and                             a
                                                                                                                                                                                  l
                                                                                                                                                                                  y                                 Faecal energy (FE)
                                                                                   Conversion Factors met from 3 to 6 December 2002 in Rome to review this                        s
                                                                                                                                                                                  i
                                                                                                                                                                                  s                                 Combustible gas (GaE) (from microbial fermentation)
                                                                                                                                                                                   
                                                                                    issue, including the implications of any recommendations for food and                         a
                                                                                                                                                                                  n
                                                                                      nutrition policies and programmes. This publication summarizes the                          d
                                                                                                                                                                                            Digestible energy (DE)
                                                                                                                                                                                  c
                                                                                               findings and recommendations of the workshop.                                      o
                                                                                                                                                                                  n                                 Urinary energy (UE)
                                                                                                                                                                                  v
                                                                                                                                                                                  e
                                                                                                                                                                                  r
                                                                                                                                                                                  s                                 Surface energy (SE)
                                                                                                                                                                                  i
                                                                                                                                                                                  o
                                                                                                                                                                                  n
                                                                                                                                                                                   
                                                                                                                                                                                  f         Metabolizable energy (ME)
                                                                                                                                                                                  a
                                                                                                                                                                                  c
                                                                                                                                                                                  t
                                                                                                                                                                                  o                                 Heat of microbial fermentation
                                                                                                                                                                                  r
                                                                                                                                                                                  s                                 Obligatory thermogenesis, i.e. excess heat relative to
                                                                                                                                                                                                                    glucose during ATP synthesis
                                                                                                                                                                                            Net (metabolizable) energy (NME)
                                                                                                                                                                                                                    Non-obligatory dietary  thermogenesis
                                                                                                                                                                                                                     
                                                                                                       ISBN 92-5-105014-7    ISSN 0254-4725                                                                         Thermogenesis due to effects of cold, drugs, hormones,
                                                                                                                                                                                                                    bioactive compounds or other stimulants
                                                                                                                                                                                            Net energy for maintenance (NE)
                                                                                                          9789251 050149                                                                                             Basal metabolism
                                                                                                                    TC/M/Y5022E/1/10.03/3000
                                                                                                                                                                                  F                                  Physical activity
                                                                                                                                                                                  A
                                                                                                                                                                                  O
                   Foodenergy–methods                                  FAO
                                                                   FOODAND
                                                                  NUTRITION
                   of analysis and                                   PAPER
                   conversion factors                                 77
                   Report of a technical workshop
                   Rome,3–6December2002
                   FOODANDAGRICULTUREORGANIZATIONOFTHEUNITEDNATIONS
                   Rome,2003
                            CONTENTS 
                            Foreword v
                            CHAPTER 1: INTRODUCTION                                          1
                               1.1 Historical background                                     1
                               1.2 Background to the technical workshop                      2
                               1.3 Rationale for the technical workshop                      4
                            CHAPTER 2: METHODS OF FOOD ANALYSIS                              7
                               2.1 Analytical methods for proteins in foods                  7
                               2.2 Analytical methods for fats in food                      11
                               2.3 Analytical methods for carbohydrates in foods            12
                            CHAPTER 3: CALCULATION OF THE ENERGY CONTENT OF 
                            FOODS – ENERGY CONVERSION FACTORS                               18
                               3.1 Joules and calories                                      18
                               3.2 Theoretical framework for an understanding of food energy 
                               conversion factors                                           19
                               3.3 Flow of energy through the body – a brief overview       20
                               3.4 Conceptual differences between metabolizable energy and net 
                               metabolizable energy                                         22
                               3.5 Current status of food energy conversion factors         23
                               3.6 Standardization of food energy conversion factors        32
                               3.7 The relationship between food energy conversion factors and 
                               recommendations for energy requirements                      33
                               3.8 Other practical implications related to the use of food energy 
                               conversion factors                                           37
                            CHAPTER 4: SUMMARY – INTEGRATION OF ANALYTICAL 
                            METHODS AND FOOD ENERGY CONVERSION FACTORS  57
                               4.1 Protein                                                  57
                               4.2 Fat                                                      58
                               4.3 Carbohydrate                                             58
                               4.4 Alcohol, polyols, organic acics and other food energy 
                               producing substrates                                         60
                             iv
                             REFERENCES 61
                             ANNEXES 67
                               I: Participants – Technical Workshop on Food Energy: Methods 
                               of Analysis and Conversion Factors                            68
                               II: Members of Working Group 5, their recommendations and the 
                               modifications to those recommendations made by the current 
                               technical workshop participants                               72
                               III: Corrections to the diet and/or standard energy requirements 
                               when using metabolizable energy (ME) or net metabolizable 
                               energy (NME) factors                                          78
                               IV: Comparisons of energy contents of breastmilk, infant formula 
                               and selected foods for infants and young children using ME and 
                               NME energy conversion factors                                    82