Numerous observational studies and their meta-analyses repeatedly confirm the association between regular breakfasts and the reduction of the risk of a number of diseases, but they cannot prove a causal relationship. The results of small and short-term intervention studies to date are inconsistent and do not confirm the significant positive effects of regular breakfasts found in observational studies.
Longer intervention studies are needed to obtain stronger evidence. However, the results of intervention studies to date may also mean that eating or skipping breakfast may be to some extent just a marker of a lifestyle that itself has a health impact.