Background & aims
Restrained food consumption may alter metabolic function and contribute to eventual weight gain; however, sex differences in these relationships have not been assessed. The objective of this study was to examine the relationship between restrained eating and insulin resistance and the influence of body mass index and sex on this relationship in a large community sample of both men and women. We hypothesized that restrained eating would be related to insulin resistance and this relationship would be influenced by sex and body mass index.
Methods
In this cross-sectional, observational study, we studied 487 individuals from the community (men N = 222, women N = 265), who ranged from lean (body mass index 18.5–24.9 kg/m2, N = 173), overweight (body mass index 25–29.9 kg/m2, N = 159) to obese (body mass index > 30 kg/m2, N = 155) weight categories. We assessed restrained eating using the Dutch Eating Behavior Questionnaire and obtained fasting morning plasma insulin and glucose on all subjects.
Results
In men, but not in women, restrained eating was related to homeostatic model assessment of insulin resistance (HOMA-IR) (p < 0.0001). Furthermore, HOMA-IR was significantly higher in men who were high- versus low-restrained eaters (p = 0.0006).
Conclusions
This study is the first to report sex differences with regard to the relationship between restrained eating and insulin resistance. Our results suggest that high restrained eating is associated with insulin resistance in men but not in women.
Abbreviations
BMI, body mass index; DEBQ, Dutch Eating Behavior Questionnaire; FPG, fasting plasma glucose; HOMA-IR, homeostatic model assessment of insulin resistance; OW, overweight; OB, obese; SAS, statistical analysis software
Obesity affects two-thirds of the United States population (Flegal, Carroll, Ogden, & Curtin, 2010). Many individuals attempt to control their weight by consciously limiting or restraining food intake. Unfortunately, restrained food consumption may alter metabolic function (Gingras et al., 2000, Keim and Horn, 2004, Laessle et al., 1989a, Laessle et al., 1989b, Pirke et al., 1990, Schur et al., 2008 and Teff and Engelman, 1996) and, in several studies, has been found to lead to eventual weight gain (Klesges et al., 1992 and Stice et al., 2005). Some studies attribute this discrepancy to decreased energy expenditure in restrained eaters (Tuschl, Platte, Laessle, Stichler, & Pirke, 1990). Other studies have examined metabolic function in the setting of restrained eating (Gingras et al., 2000, Keim and Horn, 2004, Laessle et al., 1989a, Laessle et al., 1989b, Pirke et al., 1990, Schur et al., 2008 and Teff and Engelman, 1996). Most, but not all, of these studies have found that lean women who are restrained eaters have lower fasting insulin (Pirke et al., 1990), decreased insulin resistance, increased postprandial insulin and glucose, increased insulin sensitivity (Martins, Morgan, & Robertson, 2009), and increased cephalic phase insulin response (Teff & Engelman, 1996) as compared to their non-restrained counterparts. Women who are overweight and obese (OW/OB) restrained eaters are relatively more insulin sensitive as compared to non-restrained OW/OB women (Keim & Horn, 2004). These studies give valuable insight into metabolic pathophysiology that may contribute to weight gain in some restrained eaters but notably have limitations. A majority of these studies investigate restrained eating in women, rather than including both sexes, have a relatively small sample size, and include subjects who are either lean or OW/OB but do not assess differences across the weight spectrum. Additionally, none of these studies directly compare lean to obese restrained- and unrestrained-eaters in relation to insulin resistance and no study has examined sex differences in these relationships. As differences exist between men and women with respect to insulin resistance (Geer & Shen, 2009), we contend that men and women differ with regard to the relationship between restrained-eating and insulin resistance and that these metabolic discrepancies may partially account for differential patterns of weight gain in men and women. In this study, we examine the association of restrained eating and insulin resistance and the influence of body mass index (BMI) on this relationship in a large community sample of both men and women. We hypothesized that restrained eating would be related to insulin resistance and this relationship would be influenced by sex and BMI.
