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.