Low carb diets can be effective but you need to be carful if you have suffered with depression. Your brain needs some carbs to work effectively. Slow carbs are fine but you do need them.
I have fallen foul of this before and later discovered the brain needs carbs to generate serotonin but can only do this when there is an absence of protein in the blood stream. On a high protein diet the window of oppertunity for this is quite slim.
I still have a reduced carb diet compared to most but will eat some potatoes, brown pittas, brown pasta and lots of good nuts and veggies. I know when I need carbs.
I eat lots of saturated fat including a block of cheese a week lots of butter and meat with fat in it. In my experience fat is not a problem for weight gain. Sugar is.
Excess sugar can also cause peaks and troughs which can effect depression as well as locking fat in.
IMO the caleries in/out model for weight loss is flawed.
Eat sensible amounts of good carbs (broccoli is good for me in particular) with protein. Exercise modorately and get sleep and drink lots of water.
Avoid alchohol in large quantites.
I did loose a stone or so but was not a lot over weight. I'm 5'11" and a steady 73kg. I also came off anti depressants and with the right food exercise, sleep and social life have not needed them since (consult doctor).
One note is that some (a lot) of anti depressants can cause considerable weight gain and carb cravings. In my experience also reduced my capacity for cardio exercise.
Exercise is fine for my physically and mentally but hard physical exercise releases cortisol which has negative effecton on your mental well being, so if you are recoving from depression, do try things but all in moderation and have some patience.
Another note is that you need to get your body used to burning fat, speeding up your metabolism, long steady rides with your heart in the cardio zone, get a heart rate monitor if you don't have one. This will help NOT because your have burnt X no. of calories but because your body will treat the food that you are eating differently when you have a faster metabilic rate.
I am not a dietician, medical professional or psycologist, these are things that I have researched and tried and helped me.