Sex differences in weight perception and nutritional behaviour in adults with cystic fibrosis

Good nutritional status in cystic fibrosis (CF) is associated with improved clinical status and survival. In some conditions where dietary and pharmacological treatment are important (e.g. diabetes), a combination of eating disorders and failure of treatment compliance has been reported. Cases of eating disorders have been reported in CF. Societal pressures on young women to remain slim may compromise optimum clinical management as women are content to remain underweight.

To determine whether women have different perception of their weight than men with CF and whether this manifests in different nutritional behaviour.

Confidential postal questionnaire to 1870 adults with CF in 1994 known to the Association of Cystic Fibrosis Adults (UK). Participants were asked their own weight and height, and their perception of their weight. Very underweight was defined as < 85% ideal body weight, underweight as 85-94%, normal weight as 95-104%, overweight as 105-114% and very overweight as 115% and over.

A significantly higher proportion of women than men who are very underweight (29% vs. 11%) or underweight (41% vs. 15%) saw themselves as being of normal weight or overweight. Conversely, a significantly higher proportion of men than women who were normal weight (42% vs. 19%) saw themselves as underweight. All P-values < 0.01. A significantly higher proportion of people who perceived themselves to be underweight were taking oral or enteral food supplements compared with those who did not (77% vs. 30%, P < 0.05). Multiple logistic regression showed that perception of self as underweight was the strongest predictor of taking oral or enteral food supplements (adjusted odds ratio 2.42), even after adjustment for age, sex, overall severity score, body mass index, and seeing a dietitian in the last year.

Young women with CF tend to overestimate their weight, and young men with CF underestimate their weight when compared with their actual body weight. Perception of self as underweight is reflected in nutritional behaviour, being a significantpredictor of taking oral and enteral food supplements. People working with young patients with CF should be aware of these sex differences in weight perception, and work with young women and young men with CF to achieve a realistic perception of body weight and realistic nutritional goals. There is a need for further research into body image, weight perception, eating behaviour and adherence to pancreatic enzyme supplementation and oral and enteral food supplementation in young patients with CF.