Researchers found that healthy women who skipped breakfast for two weeks ate more during the rest of the day, developed higher "bad" LDL cholesterol levels, and were less sensitive to insulin than women who ate breakfast every day.
High LDL cholesterol levels and impaired insulin sensitivity are both major risk factors for heart disease.
Although previous studies on the effects of eating or skipping breakfast in obese people may have produced conflicting results, researchers say the findings of this study show that skipping breakfast may lead to weight gain as well as increase the risk of heart disease in healthy people over time.
Researchers say skipping breakfast has become more common among adults in recent years, perhaps due to efforts to lose weight or time pressures in the morning. But at the same time, the prevalence of obesity and overweight has also dramatically increased.
In the study, which appears in the February issue of the American Journal of Clinical Nutrition, researchers examined the effects of eating or skipping breakfast on calories eaten and burned throughout the day as well as circulating insulin, glucose, and cholesterol levels in 10 healthy women of normal weight.
For two weeks, the women ate a breakfast consisting of a bowl of whole-grain cereal (Bran Flakes from Kellogg's) with 2 percent milk between 7:00 a.m. and 8:00 a.m. and then had a midmorning snack of a candy bar (Kit Kat from Nestle) between 10:30 a.m. and 11:00 a.m. The women then ate two additional meals and snacks at predetermined times every day and kept records of what they ate.
After a two-week break, the same women then followed the same protocol but skipped the early morning meal and had the cereal at lunch time (between noon and 12:30 p.m.). They then ate the other two meals and snacks at the predetermined times for another two weeks.
The results showed that when the women ate breakfast, they ate about 100 fewer calories per day (an average of 1,665 calories per day vs. 1,756 calories per day over a three-day measurement period).
Researchers also found that total and LDL "bad" cholesterol levels were significantly lower in the women who ate breakfast. Total cholesterol was 121 mg/dL in the breakfast group compared with 133 in the other group. LDL was 60 in the breakfast group and 70 in the non-breakfast group.
The women who ate breakfast also had a better insulin response to eating, suggesting that their risk of diabetes was lower.
The women's body weight didn't change significantly between the two groups during these two-week periods, but researchers say the results offer a potential mechanism by which skipping breakfast could lead to weight gain in the longer term.
In addition, the results show that the negative effects of skipping breakfast on cholesterol and insulin levels may also increase the women's risk of heart disease over time.
Sources: Farshchi, H. American Journal of Clinical Nutrition, February 2005; vol 81: 388-396.
By Jennifer Warner
Reviewed by Brunilda Nazario, MD
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