International Journal of Obesity (2003) 27, 728–734. doi:10.1038/sj.ijo.0802300

Diet and body mass index in 38 000 EPIC-Oxford meat-eaters, fish-eaters, vegetarians and vegans

E A Spencer1, P N Appleby1, G K Davey1 and T J Key1

1Cancer Research UK Epidemiology Unit, University of Oxford, Oxford, UK

Correspondence: EA Spencer, Cancer Research UK Epidemiology Unit, University of Oxford, Gibson Building, Radcliffe Infirmary, Oxford OX2 6HE, UK. E-mail:

Received 8 April 2002; Revised 4 October 2002; Accepted 28 January 2003.



OBJECTIVE: To compare body mass index (BMI) in four diet groups (meat-eaters, fish-eaters, vegetarians and vegans) in the Oxford cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford) and to investigate lifestyle and dietary factors associated with any observed differences.

DESIGN: Cross-sectional analysis of self-reported dietary, anthropometric and lifestyle data.

PARTICIPANTS: A total of 37 875 healthy men and women aged 20–97 y participating in EPIC-Oxford.

RESULTS: Age-adjusted mean BMI was significantly different between the four diet groups, being highest in the meat-eaters (24.41 kg/m2 in men, 23.52 kg/m2 in women) and lowest in the vegans (22.49 kg/m2 in men, 21.98 kg/m2 in women). Fish-eaters and vegetarians had similar, intermediate mean BMI. Differences in lifestyle factors including smoking, physical activity and education level accounted for less than 5% of the difference in mean age-adjusted BMI between meat-eaters and vegans, whereas differences in macronutrient intake accounted for about half of the difference. High protein (as percent energy) and low fibre intakes were the dietary factors most strongly and consistently associated with increasing BMI both between and within the diet groups.

CONCLUSIONS: Fish-eaters, vegetarians and especially vegans had lower BMI than meat-eaters. Differences in macronutrient intakes accounted for about half the difference in mean BMI between vegans and meat-eaters. High protein and low fibre intakes were the factors most strongly associated with increasing BMI.


body mass index, diet, vegetarian, vegan

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