August 2017 Health Bulletin

It's what you eat, not what you weigh

Consumption of energy dense foods, particularly those with a high content of unsaturated fats and sugar, predicts weight gain and greater waist circumference, which in turn increases the risk of obesity-related cancers such as breast, bowel, ovarian, endometrial, kidney, gallbladder, oesophageal and pancreatic cancer. Foods with a high dietary energy density (DED) may be associated with lower overall satiety (feeling of fullness) resulting in greater overall energy intake, whereas low energy dense diets have been reported as resulting in weight loss and less hunger compared with dietary fat restriction in a year long trial¹.

The association between energy dense foods and the incidence of obesity-associated cancers has been further explored in an analysis of data from 92, 295 postmenopausal women, aged between 50 and 79 years, who were enrolled in the Women's Health Initiative (WHI) study in the US².

DED was defined as the amount of energy (calories or kilojoules) per gram of food. Each woman's DED was assessed by self-reporting, using a food frequency questionnaire at baseline. The incidence of obesity-related cancer was self-reported at baseline and follow-up, and re-confirmed during the 14.6 +/- 5.6 years of follow-up using medical records.

Women who reported high DED intake tended to be younger, live in an area of lower socio-economic status, drink less alcohol, be less active and more likely to use anti-inflammatory medication. The risk of any obesity-related cancer was 10% greater in those who had the highest DED intake (top 20%) compared to the lowest intake (lowest 20%), although the association between DED and any individual cancer type was not statistically significant. Higher DED was also associated with a higher body mass index (BMI), waist circumference and adult weight gain.

When the analysis was broken down by BMI, a statistically significant association between obesity-related cancer and high DED was only seen in women with a normal BMI at baseline (<25kg/m2), not in overweight or obese women. The women of normal weight, with high DED also had a greater mean waist circumference.

The findings provide more support to the concept that weight management alone is not protective against obesity-related cancers. Rather, high DED foods in normal weight women appear to increase metabolic dysfunction, which is known to increase cancer risk. Some reports have associated diabetes (a known risk factor for certain obesity-related cancers) and DED, and a recent report from WHI showed a 49% greater bowel cancer risk in normal-weight women who had metabolic dysfunction³. It has been postulated that this is due to the inflammatory effects of fat tissue in the body, particularly central body fat, and metabolic dysfunction.

Limitations of this study are that the WHI participants were mainly non-Hispanic white women, well-educated and postmenopausal and the sample size was too small to evaluate associations in differing racial/ethnic groups.

The authors concluded that in normal-weight postmenopausal women, a higher DED may increase risk for obesity-related cancers, and that this risk factor may be modifiable by dietary intervention targeting energy density reduction.

References

1. Ello-Martin JA, Roe LS, Ledikwe JH, Beach AM, Rolls AM, Dietary energy density in the treatment of obesity: a year-long trial comparing 2 weight-loss diets. Am J Clin Nutr 2007 Jun;85(6):1465-77.
2. Thomson CA, Crane TE, Garcia DO, Wertheim BC, Hingle M, Snetselaar L, Datta M, Rohan T, LeBlanc E, Chlebowski RT, Qi L. Association between Dietary Energy Density and Obesity-Associated Cancer: Results from the Women's Health Initiative. Journal of the Academy of Nutrition and Dietetics. J Acad Nutr Diet. 2017 Aug 8. pii: S2212-2672(17)30624-X. doi: 10.1016/j.jand.2017.06.010. [Epub ahead of print]
3. Liang X, Margolisk, Hendryx M, et al. Metabolic Phenotype and Risk of Colorectal Cancer in Normal-Weight Postmenopausal Women. Cancer Epidemiol Biomarker Prev. 2017; 26(2):155-161