Ph.D. Thesis: FOOD INTAKE
PATTERNS AND DEVELOPMENT OF OBESITY
by Per Togo
Research Unit for Dietary Studies and Danish Epidemiology Science Centre at
Institute of Preventive Medicine,
Copenhagen University Hospital
Copenhagen County Research Centre for Prevention and Health, Glostrup University
Hospital
University of Copenhagen
Supervisors Merete Osler, MD, D.Sc. Berit L. Heitmann, dentist, Ph.D. Thorkild
I.A. Sørensen, MD, D.Sc.
Approved november 2003, University of Copenhagen, DK
SUMMARY
According to a recent estimate the prevalence of obesity has
been increasing in Denmark, and around 300 000 adult Danes are obese
today. If the increase follows the trends seen in many other Western countries,
the problem of obesity and comorbidities such as diabetes,
hypertension, osteoarthritis and some cancers will be an overwhelming challenge
for the healthcare system. The habitual diet is one of
many factors, which have been proposed to lead to the accumulation of body fat.
However, previous studies have failed to give consistent
evidence for an (energy independent) effect of macronutrients in the diet on
weight gain. Interactions between macro- and micronutrients
and the appetite regulating effect of some foods may well be of importance for
weight balance. Studying the foods as they are eaten rather
than macronutrients in isolation may better capture this interaction. Therefore,
we examined whether the combinations of foods in the diet -
food intake patterns -have an influence on weight gain.
All previously published papers studying the association
between food intake patterns and body mass index (BMI) or obesity development
was reviewed. This showed that all 30 studies were cross-sectional and the
measurement of body mass was mostly secondary to the
different prime targets of the analyses. The results of the studies were
inconsistent and the comparison was hampered by the difference in
methodology used to define the food intake patterns.
Consequently, we studied this relation in a longitudinal
design using data from the Danish MONICA studies, collected by the Research
Centre for Prevention and Health at the Copenhagen County Hospital in Glostrup
between 1982 and 1994. Food intake patterns were
identified by factor analysis on data from a food frequency questionnaire in the
participants who completed the food frequency questionnaire
as well as a 7-day diet record. The food factors were labelled after their food
composition, for men, 'Green', 'Sweet' and 'Traditional' and for
women 'Green' and 'Sweet-Traditional' and they were similar to factors found in
other studies. The factors could be reproduced using
categorised data from the diet record, and in data from the participants who
only filled in the food frequency questionnaire.
Each of the factor scores were tested for association with
current BMI, subsequent change in BMI and obesity over a period of 11 years,
while adjusting for age, education level, physical activity, smoking, parity,
(baseline BMI and previous change in BMI) and the other food
factor scores. The cross-sectional analyses showed an inverse association
between scores on the 'Sweet' or 'Sweet-Traditional' factor (men
and women, respectively) and BMI. Prospective analyses showed a significant
inverse association between baseline score on the
'Traditional' factor and subsequent 11-year BMI change for men, whereas for
women, an inverse association between baseline score on the
'Sweet-Traditional' factor and subsequent five-year BMI change was observed.
Fully adjusted analyses of the associations between factor
score changes and subsequent BMI changes or the odds of being obese at 11-year
follow-up gave no significant results. In conclusion, the
associations between food intake patterns and obesity observed in this study
were only modest and gender specific. However, the concept
of food intake patterns can be further developed for statistical analysis, and
should be applied on other data materials that include frequent
longitudinal observations of changes in body weight, to establish a more solid
evidence of the possible relation.
The PhD.-thesis is based on three published or submitted papers. They are included as the following enclosures I, II and III.
(Artikler)