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What Do Diet Quality Indices Say About Obesity?

dietary quality indices

A review was conducted to determine the association between dietary quality indices and general or abdominal obesity in adults. Insufficient evidence from the literature made it difficult to draw specific conclusions; however, the healthy eating index (HEI) was found to be inversely related to obesity.


Obesity is a serious and widespread condition characterized by excess fat accumulation that can lead to an increased risk of diseases such as, type 2 diabetes, high blood pressure, cardiovascular disease (CVD), cancer and premature death. Diet is strongly associated with obesity and can help to reduce the risk of diseases that can occur. Diet/dietary indices are a tool used to assess how well a population is adhering to a set of recommendations.

The purpose of this study published in the British Journal of Nutrition, was to review observation studies in the literature and determine the associated between dietary quality indices (DQI) and general and abdominal obesity. This study included prospective (cohort), cross-sectional and case–control studies, whereas reviews, meta-analyses, commentaries, clinical trials, editorials or duplicate publications were not used. Out of 479 articles searched, only 34 studies met the criteria for review and were from the time frame of January 1990- January 2016.

A comprehensive review of the results showed an association between weight status with the original HEI and obesity from eight cross-sectional studies, seven reported a significant relation, two studies found no correlation in women whereas one of them found a correlation in men. A different study by Tande and colleagues reports that studies in males and females revealed different correlations; for example, the relationship between the HEI score and abdominal obesity was stronger in men than in women. Additionally, a significant correlation was found between higher HEI scores and lower BMI in males but not in females. Another study by Guo and colleagues concluded that men had lower scores of HEI which increased the risk for general obesity and being overweight by 50%. However, in women, lower scores of HEI increased the risk for general obesity by 70% but not of being overweight. A general overview may imply that the HEI scores showed a better correlation with general obesity or abdominal obesity in males and a weak association in females.  Yet, despite the sex difference in weight and obesity, it should be noted that menopausal women tend to gain more weight over time than men, resulting from the potentially confounding effect of hormonal changes.

Overall, among thirteen studies on HEI, ten had the opposite relationship as expected to obesity and three had no associations at all. However, of seven studies assessing DQI, only two reported inverse associations and others had conflicting associations based on race, sex and the design of the study. Another finding based on diet worldwide was that many diet quality scores displayed a common dietary pattern of high intake of plant-based foods, as well as whole grains, moderate intakes of alcohol, and low intake of red and processed meat, salt, sweetened beverages and trans-fatty acids. When dietary intake was observed from a worldwide perspective, the major issue in developing countries were both under- and over-nutrition. Nutritional behaviour, food choice, economic cultural factors and ethnicity played major roles in obesity. For example, in a Spanish population, diet cost increased with higher observance to the HEI and higher scores of the HEI were inversely related to general obesity. Moreover, it was found that dietary habits changed in the Chinese and Hispanic individuals as they adopted new dietary behaviours as they migrated to North American countries.

The study had a few limitations that should be to taken into consideration. Even though a wide range of literature was searched, not many studies met the criteria to be considered relevant. Another limitation was that most of the studies were conducted in developed countries. This is important because other populations may differ with respect to weight reduction and acceptance of food items from dietary guidelines. On the contrary, most of the studies conclude that overall quality of diet is related to obesity and the results provide insight for future research aimed at creating strategies to improve nutrition and prevent obesity.


Written By: Seema N. Goolie, BSc

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