I had a type of weight loss surgery (called duodenal switch) that requires a very high protein, relatively high fat and much lower carb diet to accomodate nutrient malabsorption. I don't know if that change in the balance of intake was a factor, but in the first six months or so following my surgery I had quite a harsh round of depression that was clearly a biochemical issue.

I suspect that rapid weight loss was also a factor, as well as changes in how I absorbed medications.

Please note that when we talk about these types of connections, they are not *causes.* They are correlations. Why is this important to note? Because if we believe something "causes" a depression, we can fall into the trap of believing that changing that something will also *fix* the depression. Down that path lies a LOT of misinformation and frustration :-(.

IMO there are lots of things that can tip the balance of mood and send us off the deep end. It often seems like something is the straw that breaks the camel's back. *ugh*

I want to underscore NoCake's point that inadequate nutrition will play pure hell with mood. If your body is in emergency mode for any reason, mood is going to go down the tubes in no time flat. Think about when you get sick or have surgery, for example. The same is true of severe nutritional deprivation--or even less severe deprivation. Every body reads "EMERGENCY FOOD SHORTAGE" at a different point. There are no magic calorie or nutrient numbers or activity levels at which it can be predicted to happen. It's highly individual.

I'm confident, too, that if you don't lose every single pound, your sister will still be THRILLED to have you as her bridesmaid. Please be kind ot yourself :-).