Colder weather may increase cholesterol levels. The Atlantic reports research, conducted in Brazil, found an 8 percent increase occurred in colder weather over tests conducted during the summer. Original studies verified that heart attacks happen more often during winter months and the reasons could be more stress due to the holidays and strenuous activities, such as snow shoveling. Researchers believe less sun exposure in the winter may be a key to the variation since vitamin D improves the ratio of good and bad cholesterol levels. Another part of the study is the obvious dynamic of increased food consumption and less exercise in colder weather. Scientists conducted the research in a tropical climate, noting fluctuations could be greater where seasonal climate shifts are more dramatic. Fastcast: Sticky.