Audience member Laurie tells Dr. Oz that she is always hot and doesn't know why.
Dr. Oz explains how the brain monitors our body temperatures in different cases. In the case of infection, the body increases its heat as a defense mechanism to help kill the affecting bacteria. Dr. Oz further explains that other events cause our hormones to not react correctly, and that along with a couple other factors like thyroid disease and tumors, it's important to find out how long that has been happening.
Laurie further informs Dr. Oz that she has been hot her whole life, and that she has thyroid issues and cystic ovarian disease (when ovaries produce excessive amounts of male hormones, often with elevated insulin levels and obesity factors). Laurie's weight problem only contributes to her current issues, including the heat.
Dr. Oz tells Laurie that she must lose weight to help her own cause here.
Audience member Fran tells Dr. Oz that she lost 40 pounds, and ever since, Fran has been extremely cold.
Dr. Oz purports again that there are many reasons for being hot and cold, including being overweight, but another factor being that the weight is in the wrong place. Dr. Oz explains that if you don't have enough body fat, you tend to cool faster because you don't have the storage to generate the heat.