Treatment of obesity with dietary fibre: Present position and potential developments

Abstract

Obesity is one of the conditions included in the list of Fibre-deficiency disorders considered when Burkitt and Trowell developed their hypothesis of Dietary fibre deficiency as a cause of many of the diseases of the Western World. There is some suggestive evidence for a role for fibre but un travelling the relative contributions of different variables in the diet is very difficult¹ (Trowell, 1975). In any case, the problem of attempting to use fibre to facilitate weight loss in the obese is almost a totally different question to that of whether or not high fibre diets reduce the tendency to weight gain in those so predisposed. The epidemiological data may point towards a role for fibre in maintenance of normal body composition, but these data do not allow the intellectual jump to a hypothetical role in weight reduction. Nevertheless claims have been made² (Eyton, 1982) that slimming should be easier because the high-fibre diet is more filling and that weight loss will be quicker because a larger proportion of calories will be undigested. Is there supporting evidence for these mechanisms of action? (See figure). With regard to the first claim there is evidence that both obese and non-obese subjects offered high energy density and low energy density diets reached ‘satiety’ (pleasant fullness) when eating only 1570 kcalories of low energy density foods compared to 3000 kcalories of high energy density foods³ (Duncan et al., 1983). Although not specifically analysed in terms of fibre content the low energy density diet was undoubtedly higher in fibre than the high energy density diet. It has also been reported recently that ad-lib food intake following high and low fibre lunches may be significantly reduced for the rest of the day⁴ (Burley et al., 1986). It does not however follow that significant short term effects will be maintained after transfer to a high fibre diet for periods longer than the five days used by Duncad³ (Duncan et al., 1983).