A 2012 study also showed that people on a low-carb diet burned 300 more calories a day – while resting! According to one of the Harvard professors behind the study this advantage “would equal the number of calories typically burned in an hour of moderate-intensity physical activity”. Imagine that: an entire bonus hour of exercise every day, without actually exercising. A later, even larger and more carefully conducted study confirmed the effect, with different groups of people on low-carb diets burning an average of between 200 and almost 500 extra calories per day.
Some antidepressant medications can cause weight gain, especially the older tricyclic antidepressants (TCAs) such as Tryptizol, Saroten, and Clomipramine; as well as newer drugs such as Remeron (Mirtazapine). Lithium (for manic-depressive disorder) often causes weight gain. The most common antidepressants known as SSRI’s (for example Citalopram and Sertraline) usually don’t impact weight significantly. More on depression

In a way, moderate-intensity physical activity is that "magic pill" a lot of people are looking for, because the health benefits go beyond keeping your waistline trim: Not only can it reduce your risk of cancer, stroke, diabetes and heart attacks, but studies have shown that physical activity can significantly improve the moods of patients with major depressive disorders.