Is fat intake important in the public health control of obesity?

Instituto de Medicina Social–UERJ, Rua S Francisco Xavier, 524, 7o andar, Bloco E, CEP 20550-012, Rio de Janeiro, RJ, Brazil, E-mail: sichieri{at}uerj.br

Dear Sir:

The discussion between Bray and Popkin (1) and Willett (2) has strong implications for the prevention of obesity, a challenge for many countries. As in China and other developing countries, in Brazil, obesity is increasing rapidly. Data from Brazil do not support the hypothesis that dietary fat plays a major role in obesity.

Population-based national surveys from Brazil show that for the period of 1974–1989, obesity [defined as a body mass index (BMI; in kg/m²) >30] increased by 92% among men and by 70% among women (3). In 1975 the mean percentage of dietary energy from fat in Brazil was 26% (4). In a recent population-based survey conducted in Rio de Janeiro (there are no data available from a national survey), the percentage of energy from fat was 26.6% among men and 28% among women (5). Over this same time period, the prevalence of obesity in the country rose to the level found in Rio de Janeiro (Table 1). Thus, a minimal increase in the percentage of energy from fat, at least in men, was associated with a striking increasing in obesity. Also, the prevalence of persons consuming >30% of total energy as fat is not high. In Rio de Janeiro, intake of >30% of total energy as fat varied from 33% among young men to 25% among old men. For women, this percentage varied from 39% to 26% (5).

View this table:
TABLE 1.. Prevalence of overweight and obesity in 3 national surveys and in the city of Rio de Janeiro  
Data from Brazil also suggest that the associations found between fat and BMI in ecologic studies may be due to 1) the strong correlation between fat and energy and 2) the association of overall increase in food intake with fat intake. In an ecologic study of 10 Brazilian metropolitan cities included in the 1974–1975 survey, the Spearman correlation coefficient between fat intake and energy intake was 0.92 (P = 0.01) (6), the correlation between median BMI and fat intake was 0.85 (P = 0.01) (4), and the correlation between median BMI and energy intake was 0.79 (P = 0.03) (4, 7). More recent data for Rio de Janeiro indicate that consumption of almost all food groups has increased, with soda consumption increasing 268% in 20 y (8), but in this data set, there was no association of fat intake with BMI (R Sichieri, unpublished observations, 1997). Greater fat consumption in more recent data may be partially due to the differences in data collection—use of a food-frequency questionnaire in the recent survey compared with 7-d, weighed-food intake records in 1975—but this would not explain why with more available fat the association between BMI and fat disappeared. Uncoupling of activity and food intake may better explain the worldwide epidemic of obesity.

REFERENCES

1. Bray GA, Popkin BM. Dietary fat affects obesity rate. Am J Clin Nutr 1999;70:572–3 (letter).
2. Willett W. Reply to GA Bray and BM Popkin. Am J Clin Nutr 1999;70:573 (letter).
3. Sichieri R, Coitinho DC, Leão MM, Recine E, Everhart J. High temporal, geographic and income variation in body mass index among adults in Brazil. Am J Public Health 1994;84:793–8.
4. Estudo Nacional da Despesa Familiar-ENDEF. Consumo alimentar-antropometria. (National household budget survey.) Rio de Janeiro: Fundação Instituto Brasileiro de Geografia e Estatística, 1977 (in Portuguese).
5. Sichieri R. Epidemiologia da obesidade. (Epidemiology of obesity.) Rio de Janeiro: Editora da UERJ, 1998 (in Portuguese).
6. Sichieri R, Everhart JE, Mendonça GAS. Diet and mortality from common cancers in Brazil: an ecological study. Cad Saude Publ 1996;12:53–9.
7. Campana AO, Burini RC, Anselmo MA. Population surveys in Brazil: data on energy and protein intakes and on anthropometric measurements of adult people. World Rev Nutr Diet 1987;52:209–34.
8. Sichieri R, Coitinho D, Marins V, Pereira R, Moura AS. Variações temporais do estado nutricional e do consumo alimentar no Brasil. (Nutritional status and food intake trends in Brazil.) Physis 1997;7: 31–50 (in Portuguese).