this is something that highly interests me. i don't want to debate which diets are the healthiest, what low carb ketchup is coming out soon, etc. i'm talking about calories and protein/carb/fat ratios and the impacts of changing them. i am going to say FLAT OUT and claim it as ABSOLUTE TRUTH, you could lose fat eating nothing but cake and ice cream. this is NOT what i recommend AT ALL--i'm just making a point. i am going to say a few things from my own experience. when you first want to lose fat and you have a lot to lose, just a reduction of calories through diet and/or exercise WILL make you lose weight. HOWEVER, THIS IS WHAT INTERESTS ME GREATLY: as you start getting down to really low body fat levels, something weird happens which i cannot explain. by really low body fat %, i'm talking under 5%. imo, it's easy to lose fat to where your top 4 abs show. there are really 8, not 6, and getting the bottom 2 or 4 to show takes much more effort than going from 40lb overweight to 20lb overweight. anyway, when i first wanted to get ripped, i ate about 30% protein and made a weekly calorie defecit of 7000 calories. 2lb of fat is supposed to be 7000 calories. this works great at first. as my results started to become weaker (i track my weight, lean body weight, and body fat %), i upped my protein to about 40% protein and still had a calorie defecit of 7000 calories per week. keep in my mind, i update my calorie calculation weekly, so it did account for changes. HERE IS THE POINT OF MY THREAD: once you get to where your top 4 abs show great, even if you have a calorie defecit of 7000 calories per week, my weight (and lean body mass) stayed the same for weeks. eventually i had to up my protein to around 50% and keep the defecit around 7000 calories per week. keep in mind this is for making CHANGES. not a diet to live on every day. i'm not at all claiming to eat 50% protein every day. i am also not claiming that fat could not be lost eventually without upping protein, but i sure do think it would take a long time.