Postprandial energy expenditure in whole-food and processed-food meals: implications for daily energy expenditure

BACKGROUND Empirical evidence has shown that rising obesity rates closely parallel the increased consumption of processed foods (PF) consumption in USA. Differences in postprandial thermogenic responses to a whole-food (WF) meal vs. a PF meal may be a key factor in explaining obesity trends, but currently there is limited research exploring this potential link. OBJECTIVE The goal was to determine if a particular PF meal has a greater thermodynamic efficiency than a comparable WF meal, thereby conferring a greater net-energy intake. DESIGN Subjective satiation scores and postprandial energy expenditure were measured for 5-6 h after isoenergetic meals were ingested. The meals were either 'whole' or 'processed' cheese sandwiches; multi-grain bread and cheddar cheese were deemed whole, while white bread and processed cheese product were considered processed. Meals were comparable in terms of protein (15-20%), carbohydrate (40-50%), and fat (33-39%) composition. Subjects were healthy women (n=12) and men (n=5) studied in a crossover design. RESULTS There were no significant differences in satiety ratings after the two meals. Average energy expenditure for the WF meal (137+/-14.1 kcal, 19.9% of meal energy) was significantly larger than for the PF meal (73.1+/-10.2 kcal, 10.7% of meal energy). CONCLUSION Ingestion of the particular PF meal tested in this study decreases postprandial energy expenditure by nearly 50% compared with the isoenergetic WF meal. This reduction in daily energy expenditure has potential implications for diets comprised heavily of PFs and their associations with obesity.