Researchers surveyed more than 2,000 people in 2000, and again in 2009, recording their diet using a detailed questionnaire, and their vital statistics, including height, weight, BMI and activity level. The team then calculated the cost of subjects’ dietary choices through food price databases and other research.
The study’s authors wrote in their conclusion: “An increase in the energy-adjusted diet cost predicted a shift to a healthier diet and to better weight management. Diet quality strongly increased when money previously spent on unhealthy food choices such as fast food and pastry was instead spent on vegetables and fruits.”
More money, less weight
They found every €1 increase in the dietary cost per 8.36 megajoules (MJ) was associated with a 0.3kg fall in body weight. Overall, the study calculated the cost difference between the high-quality and low-quality diets as being €2.95 per day, or slightly over €1076 a year for one person.
“One might hypothesise that this would negatively influence healthy food choices, particularly in low-income families,” wrote the authors.
“This finding is of importance for health policy because it underlines the need to promote healthy diets that are accessible for all income levels, with implications for food pricing, agricultural and consumer subsidy programmes and tax policies,” they added.
The study used two different methods to measure diet quality, looking at both the types of food being consumed, and the energy density of the food consumed, with higher density indicative of a poorer diet. A reduction in diet costs resulted in falls in the quality of foods being consumed and a rise in the energy density of participants’ diets – the study’s authors said this emphasised the robustness of their data.
Prices rose for healthy food
They also noted prices in Spain of healthy foods rose faster than those of unhealthy foods over the study period: “Individuals and families facing economic constraints may be especially likely to reduce their consumption of more expensive foods, regardless of their contribution to diet quality. In addition, it is not surprising that a strong decrease in diet cost in the present study was concomitant with a dramatic decrease in the consumption of fruits and vegetables.
“On the other hand, fast food and soft drinks consumption increased in participants who greatly reduced their diet cost. This is of particular concern because soft drink and fast food consumptions are associated with less healthy dietary patterns and weight management in the present population,” the authors added.
Source: British Journal of Nutrition
Published online ahead of print, doi: 10.1017/S0007114515005048
“Association of increased monetary cost of dietary intake, diet quality and weight management in Spanish adults”
Authors: Schröder, H; Serra-Majem, L; Subirana, I; Izquierdo-Pulido, M; Fitó, M; Elosua, R