How can depression cause simultaneous anhedonia and overeating and drinking?

GettingNoSatisfact'n. "anhedonia" refers to inability to experience pleasure from things/activities that others enjoy. Some describe it as "emotional numbness" to pleasures. It is, indeed, a symptom of depression, as overeating and drinking alcohol can be. But when someone depressed reports overeating/drinking, s/he also tends to report taking little pleasure in those activities... In eating/drinking mindlessly.
General Adaption. These symptoms are related to selye's general adaptation syndrome. Depression is a stressor to your system. In response, your nervous system forces you to rest (excessively) and also to consume as many calories (often carbs) as possible in order to prepare for and cope with the stress. Hence the fatigue, avoidance, overeating, and often weight gain.