The frequency of eating breakfast has declined over the past several decades, during which time the obesity epidemic has also unfolded. Therefore, there is growing scientific interest in the possible causal role of breakfast in weight control and related disease risks. We conducted a MedLine search for studies that addressed meal frequency, breakfast consumption, and chronic disease risk. Clinical studies document that regular meal consumption can potentially reduce the risk of obesity and chronic disease through mechanisms involved in energy balance and metabolism. Many observational studies have found that breakfast frequency is inversely associated with obesity and chronic disease, but this literature does have some important limitations. Only four relatively small and short-term randomized trials have examined breakfast consumption and body weight or chronic disease risk, with mixed results. Large, long-term, randomized trials are needed.