Produced by fat cells, leptin signals to the brain how much fat is in the body, explains Dr. Scott Isaacs, medical director of Atlanta Endocrine Associates. When leptin levels are low, you tend to feel hungry, and when leptin levels are high, you tend to feel full.

Diabetes information is everywhere—blogs, online forums, small talk with friends and family, terrifying lawyer ads on TV. Keep in mind that everyone’s situation is different and some sources are more reliable than others, Dr. Isaacs says. Your diabetes care team can guide you toward the truth and help you make the best choices for your health.

There are two colors of fat, brown fat and white fat. The fat we are most familiar with is white fat, which comprises most of the fat in the body. Most of the fat in our body is white fat. White fat is a storage depot for excess calories and provides insulation. White fat produces inflammation, an unhealthy situation for the body. Brown fat is a healthy type of metabolically active fat. Brown fat is named as such because it contains a lot of energy-generating mitochondria which gives rise to the color. Brown fat is considered “good” fat because it burns calories and generates body heat. There are different types of fat. Fat is actually a series of different types of tissues with different functions. The location of fat matters and that fat in the belly is the unhealthiest type of fat that leads to many of the problems we associate with obesity including insulin and leptin resistance. But location is not the only factor that distinguishes different types of fat.

Yet another reason not to let your weight seesaw: You'll hamstring your metabolism. "My patients with the lowest metabolisms are the weight cyclers," says Scott Isaacs, MD, clinical instructor of medicine at the Emory University School of Medicine. "When you lose weight, you lose muscle and fat, but when you gain it back, it's mostly fat, which burns fewer calories."

Your circadian rhythm is the 24-hour clock that drives wakefulness and sleep. Disruptions to this biological clock have profound effects on our bodies and our hormones. New research has identified genes for the biological clock, known as clock genes, which may be the basis for metabolic diseases like obesity, diabetes and insulin resistance.