The 30% # thats been floating around is meant as a guideline for most americans. I'd say most Americans don't get their fat from olive oil and fish, but from other, more harmful sources (like meat and dairy etc.) I kept track of my calorie intake for a couple months, and I found on days when I ate less fat, i ended up eating more total calories. Fat breaks down over a long period of time so the energy is released slower.. your full onger. I see no problem with fat making up 30% of your diet. Unless you are actually trying to diet, otherwise just eat healthy versions of anything (oil instead of butter, fish instead of a burger) - these things might have the same fat content, but clearly one choice is better..