Overweight or obese women who did not eat breakfast had impaired metabolic responses after eating lunch, a small crossover study showed. On the days the women skipped breakfast, there were greater spikes in insulin and glucose levels after lunch compared with those seen on the days the women only had water in the morning, according to Elizabeth Thomas, MD, of the University of Colorado School of Medicine in Aurora.

In addition, not eating breakfast was associated with significantly higher levels of free fatty acids before lunch because lipolysis was occurring, she reported at the Endocrine Society meeting in San Farncisco. "It's possible that insulin resistance over time may predispose to further metabolic derangements and possibly progression to type 2 diabetes," she said, noting that longitudinal studies have identified a relationship between skipping breakfast and both increased weight gain and risk of type 2 diabetes.

Thomas and colleagues explored the issue in a crossover study involving 10 women, ages 25 to 40 (mean 29), who had a BMI of 27 to 35 kg/m2 (mean 31.4). Eight of the women regularly ate breakfast and two regularly skipped the meal. The study took place on 2 separate days, 1 month apart, during the follicular phase of the women's menstrual cycles.

Pre-lunch insulin levels were similar in both the breakfast and no-breakfast groups, but insulin levels increased to higher levels after lunch in women who did not eat breakfast that day. The area under the curve (AUC) was significantly greater in the no-breakfast group (P=0.001).

She recommends against either skipping meals or eating very frequent meals, the so-called nibbling diet.