Ten women (mean age, 25.5 years; mean body mass index, 23.2 kg/m2) were randomly assigned to eat or to omit breakfast daily for two weeks. After a two-week washout period, each person switched to the alternate breakfast assignment for an additional two weeks. Total energy intake was significantly lower during the breakfast period than during the no-breakfast period (p = 0.001). Resting energy expenditure did not differ significantly between the two periods. Omitting breakfast was associated with significantly higher fasting total and LDL cholesterol than was eating breakfast (3.14 and 3.43 mmol/L, and 1.55 and 1.82 mmol/L, respectively; p = 0.001). The area under the curve of insulin response to a test meal was significantly lower after eating breakfast than after omitting breakfast (p < 0.01).

Comment: These results suggest that eating breakfast causes people to consume fewer total calories during the day, without a concomitant decrease in resting energy expenditure. Eating breakfast also results in beneficial changes in cholesterol levels and insulin sensitivity. If these effects are sustained, then eating breakfast might help overweight people lose weight. Previous studies have shown that energy intake in the morning is particularly satiating, and that higher energy intake in the morning can reduce the total amount of energy ingested for the day. In contrast, energy intake late at night lacks satiating value and can result in greater overall daily energy intake.

Farshchi HR, et al. Deleterious effects of omitting breakfast on insulin sensitivity and fasting lipid profiles in healthy lean women. Am J Clin Nutr 2005;81:388-396.