I firmly believe in low carbohydrate dieting, fat doesnt make you fat carbs do mostly, like bread and potatoes. Carbs raise blood sugar and raise insulin and insulin tells you to store fat, this is why the Atkins diet works. A lot of people do low-fat, high carb and end up yoyoing on their weight because insulin forces fat to stay in your adipose cells and you get an undershoot of nutrients and after a high carb meal you have almost no blood sugar or fats to use as energy.
Many people who lose wait on high carb low cal gain weight back because they are starving and lose lean muscle mass. We can digest meat as the stomach has a pH of 2 to denature proteins and bile salts to emulsify fats. Many indiginous people eat mostly meats and vegetables and have lived healthily, and some, like the Inuit and Masai, live on basically meat only diets. So people are know to eat veggies and meats in their natural forms, but no human on earth eats a stick of wheat, but processes it into bread, which makes it the one unnatural food that is now supposedly a health food in whole grain form. However whole grains still easily spike your blood sugar and should not be consumed in excess. In fact this is how cows are fattened, the corn and wheat feed is all starch which becomes high blood sugar and promotes fat storage, cows must eat grass because they have bacteria that creates fats and proteins from fiber, this is why factory farmed animals fatten up so fast and are sick from nutrient deficiency.
If people fail on low fat diets, they really should try low-carb, and add meat back into their lives while cutting bread and rice. your body only needs small amounts of carbs like 50-120g. after a certain threshold your body goes into fat making mode because it doesnt like lots of blood sugar. Your brain is practically made out of saturated fat and cholesterol, but it is the only part of the body that NEEDS glucose to work, which your body can make from gluconeogenisis from proteins or ketosis from triglicerides.
No mammal ever eats a low fat diet, herbivorous mammals have gut bacteria that digests fibers which are indigestible polysaccarides to mammals and turns them into short-chain saturated fatty acids and "animal" proteins, in other words, the fiber is turned into fat and protein by gut bacteria, a process nearly absent in humans. All mammals thrive from high fat and high protein, you should try it as well. If you can do well on a veggie diet then whatever works for you, but if it hasnt worked you should try low-carb. most people fail on lowfat diets so pharmacueticals manufacture shit like this to make money. Watching the Weston A. Price foundation's presentation should get you to understand what we should eat and to become skeptical of mainstream government advice and inform your self.
Also look up the documentary fathead on hulu, and look up journalists like Gary Taubes and Malcolm Kendrick to see what the literature really says and watch their lectures
Sugar: the bitter truth, By Robert Lustig is also a good refernce to watch, he gives nearly endless evidence about how bad sugar is and how it makes you fat. The one thing i do disagree with him is about fibre since he did not mention the evidence or any pathways about how fiber helps you
Edit: As for gluconeogenisis and ketosis its basically the production of glucose and ketones from protein and triglycerides. glucose is basically blood sugar, ketones are basically alternative fuel that actually MAY have the heart and brain functioning more efficiently. There are apperent studies that show that ketones damage kidneys, but the studies have only been done on people who are born with bad kidneys, and ketosis makes it worse. In normal people there should be no problem with ketosis. Just think about it, in nature, would u always have food available? or would u need to cope with starving.
If you need anything further explained or clarified (yes i am a bad writer) let me know . and I am up for a friendly debate as well for meat eating