Relationship between feeding pattern and body mass index in 220 free-living people in four age groups.
OBJECTIVE: To assess the relationship between feeding pattern and body mass index in free-living humans. DESIGN AND SUBJECTS: Feeding pattern was assessed from 220 7-day weighed dietary records. 187 records were obtained from three separate existing studies, and reanalysed. These studies contained data on three age groups in the British population; Elderly group (n = 88), Middle-aged group (n = 40), Working age group (n = 59). A separate study of 13-14 year olds living in Croydon was conducted from which 33 usable diet records were collected to produce a fourth, Adolescent group. RESULTS: 'Nibbling' and greater energy intakes at breakfast were associated with a lower body mass index (BMI) in the Adolescent group. In the Middle-aged group, greater energy intakes at breakfast and lower energy intakes during the evening were associated with a lower BMI. However, when diet records which produced unreasonably low energy intakes were removed from the analysis, these relationships disappeared except for energy intakes at breakfast and BMI in the Adolescent group. CONCLUSION: It is suggested that the relationship between feeding pattern and BMI observed in the Adolescent and Middle-aged groups was caused by underestimation of 'habitual' energy intake from snacks and the omission of breakfast by females and those who were overweight. The lack of relationship in the Working age group was attributed to the fact that more individuals in this group appeared to report valid diet records. Reported energy intake was directly related to BMI in the Working age group, but was not related to BMI in the other three age groups. It is concluded that feeding pattern is not a major factor in determining BMI in humans. Also, since snacks have a relatively high sugar and low fat composition compared with meals, it is suggested that biased under-reporting of snacks by the obese could produce spurious results from free-living studies which show that obesity is related to the proportion of energy from fat in the diet.