A Cost Analysis of Three Popular Diets: the Mediterranean Diet, a Modified Paleo Diet and Intermittent Fasting

Abstract

Background: Obesity, and resulting health problems, is a growing issue facing today’s society. Weight-loss diets are popular worldwide but have shown mixed health outcomes. Current research has shown that the Mediterranean (MED) and Paleolithic (Paleo) diets as well as Intermittent Fasting (IF) have positive health outcomes. However, there is very little research surrounding the cost of all three popular diets. One factor that may influence long- term adherence is the cost of the dietary regime. Little is known about the cost of the Paleo and IF plans, but some data is available in respect of the MED diet. Objective: To compare the cost of three popular diets in today’s society - the MED diet, a modified Paleo diet and IF. Design: This thesis uses interim data from a large randomised controlled trial known as SWIFT (Support strategies for Whole-food diets, Intermittent Fasting, and Training). SWIFT recruited 250 male and female participants aged 18 years and older, who were overweight or obese (BMI>27kg/m2). The randomisation referred to different support strategies for weight- loss, but as part of the study participants were able to choose one of three dietary plans to follow; the MED diet, Paleo diet or IF. Multiple-day diet weighed records (including two weekdays/one weekend day; IF plan included one fasting/two non-fasting days) were completed at six months. Completed dietary records were entered into the dietary analysis programme Kai-culator. Each specific food/beverage item was costed for 100g, using product weights or an average weight for those items sold by unit price, and conversion factors (USDA). Pricing data for individual food items was gathered using an online supermarket shopping website or instore, and entered into Kai-culator to gain an overall daily cost for each dietary regime. Results: SWIFT included 250 participants; however only the first 112 dietary records collected from participants between June and October 2015 were used in this analysis. Thirty- two participants chose to follow the MED diet, which comprised a mean (SD) energy intake of 7531kJ (3143), with a mean protein intake equating to 18.5% of total energy, fat at 37.4% and mean carbohydrate intake at 43.3%. Sixteen participants followed the Paleo diet, which comprised a mean (SD) energy intake of 7173kJ (2706), a mean protein intake of 18.9%, a fat intake of 45.6% and mean carbohydrate intake of 34.1%. Sixty-four participants followed the IF plan, which comprised a mean (SD) energy intake of 7080kJ (4668) with mean values of 16.9% protein, 37.8% fat and 43.3% carbohydrate. The average (SD) daily cost the MED diet was NZ $11.27 (5.70), Paleo diet NZ $12.85 (5.43) and IF NZ $10.22 (6.40). There were no significant differences in costs per day between the diets (P=0.082). However, there was a significant cost difference between a non-fasting (mean (SD): $12.06 (6.55)) versus a fasting day ($6.38 (3.91)) for the IF group, (P<0.001). Conclusion: Although these differences in costs were not significant, the analysis suggests the Paleo diet is a slightly more expensive plan, while the IF plan has emerged as a potentially cheaper weight-loss intervention. Small sample sizes in the Paleo diet plan limits the potential for comparison. Analysis of the total SWIFT cohort should provide more insight.