F irst of all, when I say that I want you to eat fat, the "you" is your cells. I want your cells to eat fat. If you have excess body fat, especially visceral fat, we want your cells to eat it. If they are allowed to eat your stored fat, you need not put so much fat in your mouth, but "you" are still eating a high-fat diet. Once again, whether or not you are allowed to eat your stored fat depends on significant metabolic
hormones, mainly proper leptin function. "I want you to burn fat as fuel as opposed to glucose, whether it comes from immediate dietary intake or whether it comes from oxidation of stored fats." Maintaining proper insulin and leptin activity will allow you to burn fat. "Thus it is imperative that non-fiber carbohydrates be kept to a minimum." When you are burning stored fat you are eating and hunger will be minimized.
As far as what type of fats to eat (orally when hungry) especially pertaining to saturated fat and why, this is summarized on pages 21 and 64 of The Rosedale Diet, HarperCollins
p. 64 Saturated Fat
"This fat is primarily found in grain-fed animals, including meat, lamb, and dairy products from grain-fed animals (milk, cheese, lard, and butter) and to a lesser extent, poultry and fish. Although derived from plants, coconut oil is also high in saturated fat, but of a different kind, that may even have health benefits.
Why are grain-fed animals so high in saturated fat? Animals, like us, turn the grain that they eat into sugar, and then into saturated fat. The fat in grain-fed animals is really second generation carbohydrates. It has been known for hundreds of years that feeding grain to animals makes them fat. That is why cattle go to feed lots before they are sold, to make them fat as fast as possible. That is also what grain feeding does to us!
Unlike polyunsaturated fat, saturated fat tends to be hard at room temperature. Studies have suggested that a diet high in saturated fat may promote heart disease and insulin resistance. This is true, although some types of polyunsaturated fat can be just as bad, even worse. Saturated fat does have one advantage over polyunsaturated fats, even the good fats: It is not easily oxidized and therefore does not promote free radical production in the body. I still don't advise people to eat a huge amount of saturated fat, not if you want to lose fat. Most of the fat stored in your body is saturated fat, and, in general, it is the toughest fat to burn. If you are looking to shed pounds, it is best to limit (not eliminate) your intake of saturated fat."
"Once you become a good fat burner, you can also eat a little more saturated fat. The kind of fat you eat becomes less important because you are able to burn it off more easily."
The evidence linking saturated fat to heart disease, however, is arguable and a caveat of all of these studies is that they are done almost universally on people eating a high carbohydrate diet that prevents the proper burning of fat. The editors at HarperCollins cut this section because they thought it would create too much confusion and would be too controversial. However, for many years I have only significantly limited saturated fats for the first several months for the reasons given above and below. Recognize please that when we are talking about the amount of saturated fat to eat we are fine tuning the much more important premise of limiting non-fiber carbs and avoiding excess protein.
Please note that I do say why I limit saturated fat, at least initially (and have for decades). While I do respect his comments, Donat makes the same mistake that many before have made; that because much of what I have said (and why) has generally been original, contrary to both conventional and so-called alternative health, and thus a lone voice in the wind, people assume I must not know what I'm talking about. I was told this all-to-often almost 20 years ago when I was first to extensively talk the world over about the metabolic effects of insulin. One of these talks, "Insulin and its Metabolic Effects", was recorded by a participant, transcribed, and put on the Internet and became widely read and was, and still is, paramount in popularizing such concepts as insulin resistance and its sequelae, glycation, AGE's, low carbohydrate dieting, etc. Many people read this, and based books on these concepts over the years. I was also the first to talk and teach about the connection between leptin, leptin resistance, and mTOR and their relationship supporting a high-fat, low carbohydrate, and notably not a high-protein but at most, moderate protein diet. I believe that 15 years ago I was the first to use, very effectively I might add, a high-fat, very low carbohydrate diet to treat diabetes and cardiovascular disease, and opened the first "metabolic medicine" clinic in the country in Asheville, North Carolina and later in Boulder, Co with the Eades. I have long warned about the ill advised and detrimental health effects of fructose and the high intake of calcium that is recommended for osteoporosis that after 15 years is finally getting proper verification.
I'm not as well-known as perhaps some of my peers as I did not seek the spotlight, but freely shared my information in talks and writings with academic associates, many of whom subsequently took the information as their own and popularized it with various degrees of accuracy or inaccuracy (with the notable exception of Joe Mercola who has been very generous with his references to me, and a few others) .
Whatever I say is based on science generally much deeper than you could imagine. In this case, it's fairly straightforward and elementary, though not widely known and appreciated. Saturated fat is among the least readily oxidizable fat. That's good if one is referring to rancidity (in the body and out) but not so good if you want to oxidize it as fuel. The longer the fatty acid chain, and the more saturated the fatty acid is, in general the harder it is to burn. As one becomes more adept at burning fat, this become somewhat, but not entirely, less relevant. I have listed a few of the early and seminal references with quotes at the end.
MCTs (high in coconut oil and ghee) are the best source of fuel. Even though they are saturated, they are mostly medium chain length and can get straight into mitochondria for oxidation without needing prior shortening in peroxisomes. The monounsaturated fats found in avocados, olive oil, and nuts are also readily burned and fairly stable. Though necessary in limited quantities and readily obtained, w6 oils, found in most vegetable oils, are virtually toxic in excess. Omega 3 oils are generally deficient in people's diet and should normally be supplemented. Proper dose is fairly important as excess may be detrimental, 1-2 teaspoons/d for long-term use generally being sufficient.
The evidence that non-fiber carbohydrates cause disease and increased mortality is extremely high. The minimum daily requirement is zero. The evidence that excess protein is equally harmful is also very robust. The only controversial point would be the definition of excess. One of the PowerPoints that I posted in my last answer pertains to this. Questions pertaining to oils and fats is, to me, where the vast majority of research in nutritional science should concentrate, though I believe even here the answers in general are becoming clear.
A few of many references:
Biochem. J. (1987) 247, 531-535 (printed in Great Britain) 531 Rolf HOVIK and Harald OSMUNDSEN Peroxisomal B-oxidation of long-chain fatty acids possessing different extents of unsaturation.
"From these results it is immediately apparent that rates of peroxisomal B-oxidation increase with increasing extent of unsaturation of the carbon chain."
British Journal of Nutrition (1987), 57, 383-393 J. L EYTON, P .J. DRURY AND M . A . CRAWFORD Differential oxidation of saturated and unsaturated fatty acids in vivo in the rat.
"In comparing the oxidation of saturated and unsaturated fatty acids, [P4C] linoleic acid [1-14C] a-linolenic acid and [P4C] 0Ieic acid were oxidized at a significantly faster rate than [1-14C] stearic acid and [1-14C] palmitic acid at 24 h (P < 0'01)."
J. Lipid Res. 1982: 23 243-256. Bremer,J., and K. R. Norum. Metabolism of very long-chain monounsaturated fatty acids (22:l) and the adaptation to their presence in the diet.
"Unadapted rats and other animal species have a limited capacity to metabolize monounsaturated fatty acids with 22 carbons (22:l). Excess amounts in the diet of fats containing these fatty acids cause a transient accumulation (lipidosis) of triacylglycerol in the heart and other tissues..." "Upon continued feeding of diets with 22:l fatty acids, an adaptation takes place and the lipidosis disappears."
British Journal of Nutrition (2000), 83, Suppl. 1, S85???S90 Len H. Storlien Diet composition and insulin action in animal models
"Intake of saturated fats is strongly linked to development of obesity and insulin resistance, while that of polyunsaturated fats (PUFAs) is not. This is consistent with observations that saturated fats are poorly oxidized for energy and thus readily stored, are poorly mobilized by lipolytic stimuli, impair membrane function, and increase the expression of genes associated with adipocyte profileration (making their own home)"
Source: What Kind Of Fat On Dr Rosedales High Fat Diet