By reviewing thousands of research reports, UC scientists were able to pin down four factors that are most likely to cause overweight and obesity in America: the consumption of dietary fat, sweetened beverages and restaurant foods, and a pattern of breakfast-skipping.
The systematic review, published in the July-September issue of the University of California's California Agriculture journal, found that intake of protein, simple sugars and fruit juice, as well as food variety, portion size, snacking and frequency of eating, were not consistently related to obesity.
The peer-reviewed conclusions can help parents and health professional focus their efforts on the prime culprits in their efforts to stop the obesity epidemic currently sweeping the United States.
"Reports in the press are often conflicting and more often confuse than clarify the issue of what people should eat to prevent obesity," says lead author Lorrene Ritchie, researcher at UC Berkeley's Dr. Robert C. and Veronica Atkins Center for Weight and Health.
Since the 1970s, the prevalence of obesity has doubled among adults and tripled among children in the United States, according to the Centers for Disease Control. In California, more than 4.7 million adults were obese in 2004.
In addition to avoiding the factors that cause overweight and obesity, the study found that a diet to prevent those conditions would include lots of fiber, fruits and vegetables, and adequate calcium and dairy products.
Three years were spent systematically analyzing peer-reviewed obesity and nutrition studies published between 1992 and 2003 to isolate the main dietary factors contributing to obesity.
The current issue of California Agriculture includes four peer-reviewed articles on obesity, including the systematic review by Ritchie and five UC-affiliated colleagues; new research on possible links between food insecurity and childhood obesity in low-income Mexican-American families; new research on an association between obesity, magnesium deficiency and asthma rates; and an article on efforts by UC Cooperative Extension to organize local community coalitions for obesity prevention in California.
Source: University of California
Explore further: Two and a half thousand women could benefit from mitochondrial donation in the UK