Fat-- Do we need it?

I suspect the answer is "a little"-- but I am curious about how much and why, physiologically. I am an almost 3 months post-op RNYer, and consume about 650 calories a day-- I get 70-80g of protein, but only between 6-14 grams of fat , typically. Are there advantages to upping the fat?

I have no specifics but I do know that we need fat for fat soluable vitamins A,D,E,K. I am trying to keep my fat at 15 to 20 % of my total calories - BUT i am at 3 year out.

You are both right.  You need a little fat in your diet.  There are "essential" fatty acids just like there are "essential" proteins that must come from food as your body cannot produce these compounds.  Typically we can go 10-14 days without any fat before we start to be in danger of essential fatty acid deficiency.  With WLS the defecit of fatty acids can build up over time so the number of days before you reach essential fatty acid (EFA) deficiency can decrease (estimated at 3-5 days).  In EFA deficiency your body has a difficult time building cell walls, resulting in fragile tissue.  Since this tissue can be deep within your body and not necessarily on the surface the extent of the damage is not usually known ****il autopsy - which is a morbid thought).  The good thing is that even with a very small amount of fat you can meet your needs.  The standard clinical recommendation is minimum 5% of calories from fat and maximum 30% of calories from fat. As far as fat soluble vitamins go - it's one of those standards in chemistry, like dissolves like.  We require some fat in our diet to be able to absorb the fat soluble vitamins A, D, E, and K.  There are water soluble versions of these vitamins but they tend to be very expensive. There's the physiological answer.

I guess this means that my small amount of fat-- which works out actually to about 20%, is probably not gonna kill me. Good news!