Paradoxical nutritional deficiency in overweight and obesity: the importance of nutrient density

To the Editor: We read with interest the work presented by Markovic and Natoli, highlighting the importance of recognising the nutrient density of foods in managing overweight and obese patients.1 We present data to support their observation that it should not be assumed that a patient who is overweight or obese has a nutritionally adequate diet.

Our data were obtained as part of the Geelong Osteoporosis Study from an age-stratified sample of men randomly selected from electoral rolls for the Barwon Statistical Division in Victoria. Dietary intake was estimated using a food frequency questionnaire developed by the Cancer Council Victoria.2 Basal metabolic rate (BMR) was estimated from the Schofield equations, based on age and weight. Data were excluded if the ratio of energy intake (EI) (from food and alcohol combined) to BMR was < 0.9. The sample comprised 1175 men aged 20–93 years (median age, 56 years [interquartile range, 39–73 years]; mean weight, 81 kg [SD, 14 kg]; mean height, 1.75 m [SD, 0.07 m]). Participants were grouped by body mass index (BMI) into three categories: normal weight (BMI < 25 kg/m2), overweight (BMI 25.0–29.9 kg/m2) and obese (BMI ≥ 30 kg/m2). Estimates of physical activity were derived from self-report. Written, informed consent was obtained from participants, and the study was approved by the Barwon Health Human Research Ethics Committee.

We investigated the breakdown of macronutrients, vitamins and minerals listed in the “virtual” case report presented by Markovic and Natoli1 and expressed intakes as a percentage of recommended dietary intake (RDI).3,4 Despite adequate EI, the diets of men in all BMI categories were low in zinc, calcium, folate and fibre (Box).

We acknowledge that there are limitations posed by self-reported dietary intakes and physical activity levels. The EI–BMR ratio decreased with increasing BMI (median [interquartile range], 1.4 (1.2–1.7), 1.3 (1.1–1.6) and 1.2 (1.0–1.5) for normal weight, overweight and obese subjects, respectively), suggesting that under-reporting may have been more common with increasing BMI. We also acknowledge that RDIs are not thresholds for dietary deficiencies. Within these constraints, however, these data suggest that where there are nutritional shortcomings in diets, they are not limited to men of normal weight-for-height, but are also apparent among those who are overweight and obese. These shortcomings suggest that nutrient-dense foods, such as whole grains and vegetables (particularly leafy green vegetables) are underconsumed, while processed foods with high saturated fat and salt content are consumed excessively. These observations underscore the importance of recognising the nutrient density of foods so that nutrition is not compromised when EI is restricted.